libretro wrapper for desmume NDS emulator.

Build with 'make -f Makefile.libretro'.

Save games are stored in the system directory reported from the frontend. If one isn't provided whatever '.' resolves to will be used.
Tested on OS X and Android, should work on linux, may not work on windows yet.

If building for X86/X64 platforms put DESMUME_JIT=1 in environment to enable JIT CPU core.

Core Options
 
 * desmume_screens_layout: Main is the top screen, and ext is the touch screen
  1.  main_top_ext_bottom
  2.  main_bottom_ext_top
  3.  main_left_ext_right
  4.  main_right_ext_left

 * desmume_pointer_type:
  1.  relative - Mouse style input
  2.  absolute - Touch screen style input