Remove patch dependencies on Windows and Mac platforms to facilitate building #300
Description
On Linux Issue #231 patch is mandatory. However on Windows and Mac this is not required. Update patch.py so that this patch is applied only on Linux.
Also Issue #251 patch could be removed on Windows/Mac temporarily to facilitate building on these platforms. Either way this patch is going to be merged in upstream, so this funcionatlity would be re-introduced soon. Just update DragData (SetImage, GetImage, HasImage) documentation that this is Linux-only for now.
Issue #125 patch seems that it won't work anymore with latest CEF. See the latest comment in that issue for details. However this can stay untouched in patch.py and be applied for all platforms. It doesn't matter if it fails.