Tilengine as libretro core with LUA games

[megamarc]

Yes I was thinking about how to integrate tilengine as a libretro core for some time but I didn't know how to handle loadable games. The conversation about lua gave me the missing piece
The integration itself was quite simple:

• removed all the built-in windoinwg support (Window.c and GaussianBlur.c), and libSDL2 dependency,
  
• added a libretro.c module that implements both the client-side to retroarch, and the host-side of lua scripts
  

Everything else are the same tilengine modules without any modification. I created a separate branch to not mess up the main project, but it can be maintained as two separate makefiles of the same codebase with minimal differences.

The difficult part is debugging the lua script. This two-way integration -retroarch hosts tilengine_libretro, who in turn hosts the lua script-. This setup is far from your typical "launch your application and set up breakpoints". I'll give a look to your recommended "ZeroBrane Studio" and "Decoda" IDE. However I won't spend much time on this project, once I get something fully working I'll move to work on other ideas I have. Managing to get a Lua debugger working inside this chain of hosts can be more complex than completing tilengine_libretro itself.