CSG Support for Godot!

-Missing Icons
-Missing freezing option (for baking light and faster load)
-Missing a way to export from Godot (GLTF2?)
-Probably buggy (may freeze editor, can be worked around easily, but let me know if this happens so it's easier to catch bugs)
Happy testing!

modules/csg/SCsub

@@ -0,0 +1,9 @@
+#!/usr/bin/env python
+
+Import('env')
+Import('env_modules')
+
+env_csg = env_modules.Clone()
+
+# Godot's own source files
+env_csg.add_source_files(env.modules_sources, "*.cpp")