Add all relevant KV pairs to Desktop Entry file

This commit extends the RetroArch desktop entry
file—responsible for integrating the app with
Linux desktop environments—to include all relevant
properties. Some notable aspects:

- **`TryExec`**/**`Exec`**: TryExec _should_
  contain the canonical path to the executable,
  however the RA buildsystem lacks a ready
  mechanism for populating the correct value for
  the target at build time, so we fallback to
  searching $PATH here. To Exec we add the %F
  token, meaning that RA is a "file handler" that
  users are able to drag files onto the launcher
  icon that become arguments to the launch command.
- **`MimeType`**: This key determines which file
  extensions the system should offer to open with RA.
  It should be regularly reviewed for any new MIME
  registrations which need to be represented going
  forward.
- **`PrefersNonDefaultGPU`**: Linux by default offers
  hardware to processes in order from least capable to
  most performant. This key reverses that behavior so
  more demanding emulation cores will run more
  smoothly.
- **`SingleMainWindow`**: Changes the default behavior
  when the launcher is clicked while an instance is
  already running from launch a second instance to
  elevate the main window of the already running one.

Version 1.5 of the Freedesktop [Desktop Entry
Specification](https://specifications.freedesktop.org/desktop-entry-spec/latest/) was the reference for these changes.

Signed-off-by: Peter J. Mello <admin@petermello.net>

com.libretro.RetroArch.desktop

@@ -1,16 +1,82 @@
 [Desktop Entry]
-Version=1.0
-Name=RetroArch
-GenericName=Frontend for the libretro API
+Version=1.5
 Type=Application
-Comment=Frontend for emulators, game engines and media players
+Name=RetroArch
+GenericName=Game emulator frontend
+GenericName[ar]=واجهة ألعاب متعددة المحاكيات
+GenericName[bg]=Интерфейс за игри с няколко емулатора
+GenericName[cs]=Herní rozhraní pro více emulátorů
+GenericName[da]=Interface til spil med flere simulatorer
+GenericName[de]=Schnittstelle für Spiele auf verschiedenen Emulatoren
+GenericName[el]=Διεπαφή παιχνιδιών πολλαπλών εξομοιωτών
+GenericName[es]=Interfaz para emuladores de juegos
+GenericName[et]=Mitme emulaatori mänguliides
+GenericName[fi]=Peli-emulaattorin käyttöliittymä
+GenericName[fr]=Interface de jeu à émulateurs multiples
+GenericName[hu]=Több emulátoros játékfelület
+GenericName[id]=Antarmuka permainan multi-emulator
+GenericName[it]=Interfaccia di gioco a vari emulatori
+GenericName[ja]=マルチエミュレーター・ゲーミングインターフェース
+GenericName[ko]=멀티 에뮬레이터 게임 인터페이스
+GenericName[lt]=Kelių emuliatorių žaidimų sąsaja
+GenericName[lv]=Vairāku emulatoru spēļu saskarne
+GenericName[nb]=Grensesnitt for spill med flere emulatorer
+GenericName[nl]=Interface voor gamen met meerdere spelers
+GenericName[pl]=Interfejs do gier na wielu emulatorach
+GenericName[pt-br]=Interface de jogos com vários emuladores
+GenericName[pt-pt]=Interface para muitos emuladores de consolas de jogos
+GenericName[ro]=Interfață de joc cu mai multe emulatoare
+GenericName[ru]=Игровой интерфейс с несколькими эмуляторами
+GenericName[sk]=Rozhranie pre hry s viacerými emulátormi
+GenericName[sl]=Igralni vmesnik za več emulatorjev
+GenericName[sv]=Gränssnitt för spel med flera emulatorer
+GenericName[tr]=Çoklu emülatör oyun arayüzü
+GenericName[uk]=Ігровий інтерфейс з декількома емуляторами
+GenericName[zh-hans]=多模拟器游戏界面
+GenericName[zh-hant]=多電腦遊戲介面
+Comment=Unified frontend for many game console emulators, frameworks and media players
+Comment[ar]=واجهة أمامية موحدة لمجموعة واسعة من محاكيات وحدات التحكم في الألعاب وغيرها من أطر الألعاب أو مشغلات الوسائط
+Comment[bg]=Унифициран фронтенд за широк набор от емулатори на игрови конзоли и други рамки за игри или медийни плейъри
+Comment[cs]=Jednotný frontend pro širokou škálu emulátorů herních konzolí a dalších herních frameworků nebo přehrávačů médií
+Comment[da]=En samlet frontend til en lang række spilkonsol-emulatorer og andre spilframeworks eller medieafspillere
+Comment[de]=Ein einheitliches Grafik-Interface für eine breite Palette von Spielkonsolen-Emulatoren und andere Spiele-Frameworks oder Media-Player
+Comment[el]=Ένα ενοποιημένο γραφικό frontend για ένα ευρύ φάσμα εξομοιωτών κονσολών παιχνιδιών και άλλων πλαισίων παιχνιδιών ή media players
+Comment[es]=Interfaz gráfica unificada para numerosos emuladores de videoconsolas y otros entornos de juego o reproductores multimedia
+Comment[et]=Ühtset eesliidest paljude mängukonsoolide emulaatorite ja muude mänguraamistike või meediamängijate jaoks
+Comment[fi]=Yhtenäinen etusivu monille pelikonsoliemulaattoreille ja muille pelikehyksille tai mediasoittimille
+Comment[fr]=Interface graphique unifiée pour un large éventail d'émulateurs de consoles de jeux et d'autres logiciels de jeux ou de lecteurs multimédias
+Comment[hu]=Egységes grafikus frontend játékkonzol-emulátorok és egyéb játék keretrendszerek vagy médialejátszók széles skálájához
+Comment[id]=Antarmuka grafis terpadu untuk beragam emulator konsol game dan kerangka kerja game atau pemutar media lainnya
+Comment[it]=Un frontend grafico unificato per un'ampia gamma di emulatori di console e altri framework di gioco o lettori multimediali
+Comment[ja]=幅広いゲーム機エミュレーターやその他のゲームフレームワーク、メディアプレーヤー用の統一されたグラフィカルフロントエンド
+Comment[ko]=다양한 게임 콘솔 에뮬레이터 및 기타 게임 프레임워크 또는 미디어 플레이어를 위한 통합 그래픽 프론트엔드
+Comment[lt]=Suvienodinta grafinė prieiga, skirta įvairiems žaidimų konsolių emuliatoriams ir kitoms žaidimų programoms ar medijos grotuvams
+Comment[lv]=Vienota grafiskā saskarne plašam spēļu konsoļu emulatoru un citu spēļu ietvaru vai multivides atskaņotāju klāstam
+Comment[nb]=En enhetlig grafisk frontend for et bredt utvalg av spillkonsollemulatorer og andre spillrammeverk eller mediespillere
+Comment[nl]=Een uniforme frontend voor een breed scala aan spelconsole-emulators en andere gameframeworks of mediaspelers
+Comment[pl]=Ujednolicony interfejs graficzny dla szerokiej gamy emulatorów konsoli do gier i innych platform do gier lub odtwarzaczy multimedialnych.
+Comment[pt-br]=Um front-end gráfico unificado para diversos emuladores de console de jogos e outras estruturas ou reprodutores de mídia
+Comment[pt-pt]=Interface gráfica unificada para vários emuladores de consolas de jogos e outras estruturas de jogos ou leitores multimédia
+Comment[ro]=Un frontend grafic unificat pentru o gamă largă de emulatoare de console de jocuri și alte cadre de jocuri sau playere media
 Comment[ru]=Графический интерфейс для эмуляторов, игровых движков и медиаплееров
-Comment[fr]=Interface graphique pour émulateurs, moteurs de jeu et lecteurs multimédia
-Comment[de]=Front-End für Emulatoren, Spiel-Engines und Mediaplayer
+Comment[sk]=Jednotný grafický frontend pre širokú škálu emulátorov herných konzol a iných herných rámcov alebo prehrávačov médií
+Comment[sl]=Enoten grafični vmesnik za številne emulatorje igralnih konzol in drugih igralnih ogrodij ali predvajalnikov medijev
+Comment[sv]=En enhetlig grafisk frontend för ett brett utbud av spelkonsolemulatorer och andra spelramverk eller mediaspelare
+Comment[tr]=Çok çeşitli oyun konsolu emülatörleri ve diğer oyun çerçeveleri veya medya oynatıcıları için birleşik bir grafik ön uç
+Comment[uk]=Уніфікований графічний інтерфейс для широкого спектру емуляторів ігрових консолей та інших ігрових фреймворків або медіаплеєрів
+Comment[zh-hans]=适用于各种游戏控制台模拟器和其他游戏框架或媒体播放器的统一前端
+Comment[zh-hant]=適用於多種遊戲主機模擬器和其他遊戲框架或媒體播放器的統一前端
+TryExec=/usr/bin/retroarch
+Exec=retroarch %F
 Icon=com.libretro.RetroArch
-Exec=retroarch
-Terminal=false
-StartupNotify=false
-StartupWMClass=retroarch
-Keywords=multi;engine;emulator;xmb;
 Categories=Game;Emulator;
+MimeType=application/vnd.efi.img;application/vnd.nintendo.snes.rom;application/x-amiga-disk-format;application/x-atari-2600-rom;application/x-atari-7800-rom;application/x-atari-lynx-rom;application/x-ccd;application/x-cso;application/x-dosexec;application/x-dreamcast-rom;application/x-gameboy-color-rom;application/x-gameboy-rom;application/x-gamecube-rom;application/x-gamegear-rom;application/x-gba-rom;application/x-genesis-32x-rom;application/x-genesis-rom;application/x-hex;application/x-isz;application/x-mame-chd;application/x-msx-rom;application/x-n64-rom;application/x-neo-geo-pocket-color-rom;application/x-nes-rom;application/x-nintendo-3ds-rom;application/x-nintendo-ds-rom;application/x-nrg;application/x-pc-engine-rom;application/x-saturn-rom;application/x-sega-cd-rom;application/x-sega-pico-rom;application/x-sg1000-rom;application/x-sms-rom;application/x-virtual-boy-rom;application/x-wii-rom;application/x-wonderswan-color-rom;application/x-wonderswan-rom;
+Keywords=retro;gaming;emulator;console;
+PrefersNonDefaultGPU=true
+SingleMainWindow=true
+StartupNotify=true
+StartupWMClass=retroarch
+DBusActivatable=false
+Hidden=false
+NoDisplay=false
+Terminal=false