Added the environment variable SDL_MOUSE_NORELATIVE to completely disable relative mouse motion if the application desires it.  UNDOCUMENTED!!
Added the environment variable SDL_MOUSE_NORELATIVE to completely disable
relative mouse motion if the application desires it.  UNDOCUMENTED!!

--HG--
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%4079

aduros/SDL,cebash/SDL_PSL1GHT,aduros/SDL,aduros/SDL,aduros/SDL,aduros/SDL,cebash/SDL_PSL1GHT,cebash/SDL_PSL1GHT,cebash/SDL_PSL1GHT,cebash/SDL_PSL1GHT