Batch of Bugfixes

-=-=-=-=-=-=-=-=-

-Fixed Export UV XForm (should work now). #923
-Fixed enforcement of limits in property editor. #919
-Fixed long-standing bug of export editings in script inheritance. #914, #859, #756
-Fixed horrible error reporting in shader language. #912
-Added kinematic collision with plane (please test well). #911
-Fixed double animation track insert when using 2D rigs. #904
-VKey updates offset parameter in sprite edition. #901
-Do not allow anymore a script to preload itself. (does not fix #899, but narrows it down)
-Avoid connection editor from overriding selected text. #897
-Fixed timer autostart. #876
-Fixed collision layers in 3D physics. #872
-Improved operators in shader #857
-Fixed ambient lighting bug #834
-Avoid editor from processing gamepad input #813
-Added not keyword #752

Please test!

scene/3d/visual_instance.cpp

@@ -359,13 +359,13 @@ void GeometryInstance::_bind_methods() {
 GeometryInstance::GeometryInstance() {
 	draw_begin=0;
 	draw_end=0;
+	for(int i=0;i<FLAG_MAX;i++) {
+		flags[i]=false;
+	}
+
 	flags[FLAG_VISIBLE]=true;
 	flags[FLAG_CAST_SHADOW]=true;
 	flags[FLAG_RECEIVE_SHADOWS]=true;
-	flags[FLAG_BILLBOARD]=false;
-	flags[FLAG_BILLBOARD_FIX_Y]=false;
-	flags[FLAG_DEPH_SCALE]=false;
-	flags[FLAG_VISIBLE_IN_ALL_ROOMS]=false;
 	baked_light_instance=NULL;
 	baked_light_texture_id=0;
 	VS::get_singleton()->instance_geometry_set_baked_light_texture_index(get_instance(),0);