chg: ENABLE_THREADS=1 for windows,  small reorganize CMakeLists.txt for easier merge to next
chg: mapgen: reorganize layers and floatislands
chg: mapgen: remove copypasted generateFloatIslands
fix: Crashing when no games installed
Merge pull request #127 from donat-b/fix_nil_id_crash

fix: Crashing when no games installed
fix: Minor fixes for singleplayer menu
Merge pull request #128 from donat-b/mainmenu

fix: Minor fixes for singleplayer menu