Remove .gitignore entries for subprojects that no longer exist

.gitignore

@@ -1,12 +1,8 @@
-
-/snes9xgit
-
 **/.vs/**
 **/.vscode/
 **/bin/**
 **/obj/**
 /output/**
-/output64/**
 /packaged_output
 /result
 /test_output
@@ -24,35 +20,15 @@
 *.filters
 *.opendb
 
-/BizHawk.Client.EmuHawk/tools/TAStudio/HistoryBox.Designer.cs
-/BizHawk.Client.EmuHawk/tools/TAStudio/HistoryBox.cs
-/BizHawk.Client.EmuHawk/tools/TAStudio/HistoryBox.resx
-
-
 /src/BizHawk.Tests*/res/*_artifact
 /src/BizHawk.Tests*/res/fw
 
-/Build/*.vshost.*
-
 /Dist/*.zip
 
-/LuaInterface/LuaInterface/Properties
-/Version/bin
-/Version/obj
-/attic/PsxHawk.API/Release
-/attic/PsxHawk.Core/Debug
-/attic/PsxHawk.Core/Release
-/genplus-gx/libretro/msvc/ipch
-
-/libmupen64plus/mupen64plus-video-z64/projects/msvc11/snes9xgit
+# mupen64plus-win32-deps is a submodule, so ignores should be in that repo
 /libmupen64plus/mupen64plus-win32-deps/SDL-1.2.14/docs
 /libmupen64plus/mupen64plus-win32-deps/SDL-1.2.14/docs.html
 
-/libsnes/vs2015/.vs
-/libsnes/vs2015/.obj
-
-/References/*.xml
-
 *.opensdf
 *.user
 *.suo
@@ -63,27 +39,17 @@
 .hgignore
 .hgtags
 
-/LuaInterface/Lua/src/.libs
-/LuaInterface/Lua/src/Release-LUAPERKS
-/LuaInterface/Release-LUAPERKS
-
 ExternalCoreProjects/Virtu/bin/*.*
 /psx/octoshock/bizhawk/Win32
 /psx/octoshock/bizhawk/x64
 /psx/octoshock/bizhawk/*.opendb
 
 **/StyleCop.Cache
-libsnes/vs2015/libsnes.VC.db
 waterbox/**/*.wbx
 waterbox/**/*.wbx.in
-/BizHawkTool_template.zip
-
-mono_crash*
 
 .idea
 
 packages
 
-BizHawk.Emulation.Common/BizHawk.Emulation.Common.csproj.nuget.*
-BizHawk.Emulation.Common/project.assets.json
 launchSettings.json