Fallback to KeyboardEvent property `charCode` is absence of both `key`
and `char` for retrieval of unicode value.
(cherry picked from commit 45b90f16ca)
-fixed TouchScreenButton with stretch2d
-fixed(?) OSX crash on startup (test!!)
-compilation fixes on windows
-CollisionPolygon editor works again
-find buttons en find dialog
-TileMap editor cleanup (removed "error", made nicer)
-viewport flicker fixed
-make .scn default extension for saving scenes
-export the rest of the network classes to gdscript