Fixed some issues with the map. Also added an indestructible version

-Fixed texture misalignments
-Reduced the gibs created by the doomspire towers
-Disabled shadows for the towers (for performance)
-Added cubemaps

-fixed typo with gma file and added the map icon properly

-Renamed the .gma file to the actual name of the map, I embarrassingly left it as "mymap.gma" :)
-Added a thumbnail to the map (forgot to do that)

Initial addon creation.