Merge pull request #60 from melchips/master

[OpenGL] optimized rendering (map split in chunks, only chunks around camera are rendered)
[0.0-39] disabled the preliminary 'smooth shading' in softgm for now
Added chunks rendering options in game engine config files and fix for chunks rendering per frame count
Quick fix for /gmode command to prevent server crash with bad arguments (such as a char instead of a digit)