* Replace C++ comments into C comments
* Move INLINE out of Makefile.common, move to fceu-types.h
An INLINE define is still existing in Makefile.common for msvc (dont
have a way to to test that). Moved the rest into fceu-types.h using the
one already existing from emu2413.h.
* Increase maximum volume for apu channels
* Add option to enable/disable audio channels
Audio options are backports from FCEUX. Options are set as on/off toggle for each apu channel.
Compile with DEBUG=1 to see options.
* Add missing audio state vars, fix for hq audio when using runahead
* Additional checks for save ram (battery)
* Cleanup
* Update libretro header
