Shuffle mode

[mmontag]

Shuffle mode (toggle button) that works similar to Winamp.

• When toggled on, generates a new shuffle order for current context.
• When toggled off, play context switches to folder of the current song, so the songs can be continued in order (may be slightly problematic for single-song folders)
• The "Shuffle Play" button is actually a special case of shuffle mode, since it includes all subfolders recursively.