Merge pull request #12 from heuripedes/master

(Haiku) Fix build
Add alternate controllers
Make the setting per pad
Merge pull request #13 from fr500/master

Add alternate controllers
Update libretro.h
Update Makefile
Add Makefile.common
Implement input descriptors
Build fix
Turn controller_layout static
'Invalid Cheat code' - report RETRO_LOG_ERROR
Add DEBUG flag