OSX: Fixed Playlist rendering bugs, added Playlist header.

- On OSX, the playlist header is now styled correctly, and indicates the
playlist index + playlist count.
- On OSX, removed playlist button from the toolbar.
- Fixed bugs in ListViewControlBase when the header is not drawn.
- Set new background/selected colors for PlaylistListViewControl.
- Added CreateDrawingResources method for PlaylistListViewControl and
SongGridViewControl to prevent recreating brushes over and over again.
- A bit of code cleanup
Added generic EqualizerPresetGraphControl control.

- Added new DrawLine method in IGraphicsContextWrapper, implemented on
OSX and iOS.
- iOS does not use the new generic control yet, this will replace the
control on iOS and Android.