add viewport.get_camera_2d()

* there is now a more clear distinction between camera_2d and camera_3d functions in the engine code
* simplified camera2d's exported interface - now everything happens directly with the 'current' variable and make_current and clear_current are no longer exposed- there were some situations where calling one instead of set_current would result in incomplete results
* rebased to current godot master

0 files changed, 0 insertions, 0 deletions