2D Animation Improvements

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

-Ability to set 2D nodes as bones
-Abity to set 2D nodes as IK chains
-2D IK Solver
-Improvements in the UI for adding keyframes (separate loc,rot,scale buttons)

core/math/math_2d.cpp

@@ -74,7 +74,7 @@ float Vector2::distance_squared_to(const Vector2& p_vector2) const {
 
 float Vector2::angle_to(const Vector2& p_vector2) const  {
 	
-	return Math::atan2( x-p_vector2.x, y - p_vector2.y );
+	return Math::atan2( tangent().dot(p_vector2), dot(p_vector2) );
 }
 
 float Vector2::dot(const Vector2& p_other) const {
@@ -594,6 +594,10 @@ Matrix32 Matrix32::rotated(float p_phi) const {
 
 }
 
+float Matrix32::basis_determinant() const {
+
+	return elements[0].x * elements[1].y - elements[0].y * elements[1].x;
+}
 
 Matrix32 Matrix32::interpolate_with(const Matrix32& p_transform, float p_c) const {