Update README / SuperTux 0.3.0

SVN-Revision: 4498
Add .gitignore and autogen-clean.sh
Fixes for gcc3 and newer compilers
Fixes for gcc4.4 and newer compilers
Fix for gcc4.6 and newer compilers
Add more missing headers
Squirrel 2.2.4 gcc4.7 fixes
Add missing header to eliminate the uint16_t errors
Fix useless warnings using most locales

This actually addresses two issues:

Consider blank lines to be comments, skip over them rather than
attempting to read keywords there.

Empty a token when the comment is enountered -- the comment
is not necessarily followed by a keyword, but it can be an EOF.
Disable console
Replace OpenGL with SDL
Update supertux-nogl.diff
Merged rev 4503 into 0_3_x: Fixed broken bonus2/level6.stl

(stacked iceblocks at the start may have worked in ms1 but certainly doesn't
any longer)
Use 640x480 resolution by default