Fixes Song bug.

I found strange song bug on WinDx platform and makes a solution. This bug is in the call of method MediaPlayer.Play. It play song once but at another time(closing and another runs of a game) - it emit exception at MediaFactory.GetService in internal PlaySong method - "Not supported Interface". It emits exception not always but during some period of time - after this period it play song once more and again run that time period. Probably this is Sharpdx internal problem or monogame does not disposes com-interfaces correctly...  In debug mode when you set debugging point on this method it load interfaces correctly but if not - this exception emits. And If you call it once again after this exception in try/catch- it loads correctly. 

Also im added Obsolete atribute to Keyboard.GetState(PlayerIndex) - this method is dublicate GetState and must be deleted in the future versions - I marked it obsolete for make attention to developers.