Merge pull request #1 from alexp-sssup/master

Minor fix to build with duetto 0.9.1
Refactored main. Introduced GameHandler

* Now there are separate main files for the platforms
* Dropped main() for emscripten
Removed my gl wrapper and used duetto webGLES
Using new duetto toolchain: not hardcoded paths
Box2D usescustom type-aware StackAllocator
Refactored main(duetto, pc) and handlers
Update for duetto 0.9.3 (no duetto.js)
Update TODO
Removed double lambda for drawing pieces in graphichandler
Preliminary working emscripten
Emscripten build: do not check for host glfw,glew

Emscripten does not provides pkg-config files for these libraries,
but it supports them, provides headers and linkage.
Therefore we simply avoid checking their presence in cmake.
Client use emscripten or duetto based on url
Inputhandler works with emscripten

Inputhandler now uses GLFW keyboard callback API.
Some code has been merged with duetto and the whole class has
been restructured
Request AA and (eventually) fullscreen with GLFW3
Removed duetto webgl-util.js with an eval trick
emscriptenbuild.sh: avoid rebuilding everything
Implement esc termination in duetto & emscripten
Unload inputhandler
Added fork me on github
Updated index.html: both emscripten and duetto logo