introduce Storage abstraction interfaces
use Storage i/f to load zip and 7z archives, cdi/cue/gdi/chd media,
cheats and to find custom textures.
Use android file picker to add storage. Request persisted access perms.
jni helper classes.
Issue #813
Verify md5 of flash, eeprom, vmus if no savestate used
Use chd header SHA1 as digest
Load .state.net state file at start
Force real BIOS for some games
Flyinghead