Fixed CMakeLists.txt file
Merge pull request #147 from xycaleth/master

Fixed CMakeLists.txt
Merge remote-tracking branch 'upstream/master' into sdl_sp
Fix for rain etc. falling extremely slowly in MP in a map with a portal skybox

as seen on e.g. yavin2
Merge branch 'master' into sdl_sp
cmake now looks correctly for SDL2