OpenTK.GLWpfControl 4.3.0

Made each GLWpfControl have it's own OpenGL context allowing different controls to have different context settings. (@NogginBops) Enabled multisample anti-aliasing though GLWpfControlSettings.Samples. (@NogginBops) Implemented IDisposable for GLWpfControl that allows native DirectX and OpenGL resources to be freed. (@NogginBops) Made GLWpfControl have Focusable be true by default, solving a lot of the keyboard input event issues. (@NogginBops) Deprecated GLWpfControlSettings.GraphicsContextFlags in favor of GLWpfControlSettings.ContextFlags. (@NogginBops) Deprecated GLWpfControlSettings.GraphicsProfile in favor of GLWpfControlSettings.Profile. (@NogginBops) Added GLWpfControlSettings.SharedContext to allow context sharing. (@NogginBops) Deprecated GLWpfControl.CanInvokeOnHandledEvents and GLWpfControl.RegisterToEventsDirectly, updated readme to reflect this. (@NogginBops) Fixed rounding issues related to DPI scaling. (@NogginBops, @5E-324) Updated to depend on OpenTK 4.8.2. (@NogginBops, @softwareantics) Fixed memory leak where DirectX resouces would never be freed. (@NogginBops)