Cleaning up Rect struct
Added proper method descriptions
Obsoleted Rect.GetEdges, Rect.EdgeSize, use Margin struct
Removed Rect.Add( Vector3 ) (Vec2 overload works with Vec3, no addons broke)
Added Rect,Add( Vector2 )
Obsoleted all Expand/Contract overloads, use Shrink/Grow
Rework how asset browser thumbs are sized
Added Rect = Rect.Contain( size, align )
Added Pixmap.Size mimicking Rect.Size