OpenGL Framebuffer Object (FBO) support available to modules

ToME now uses a FBO to do a full map shader that can blur, colorize, ...
Low hit point warning now displays a red "glow" around the map edges, intensifying as life gets lower


git-svn-id: http://svn.net-core.org/repos/t-engine4@841 51575b47-30f0-44d4-a5cc-537603b46e54