Added matrix handling code and puck/mallet drawing code.

a) Add linmath.h as a GitHub submodule.
b) Change libzlib/ to zlib/.
c) Update notes and .gitignore files and update project files.
d) Added matrix setup code for displaying the air hockey table at an angle, and added support to the Android, iOS, and Emscripten builds.
e) Added drawing of pucks and mallets.