Changes based on ChoiZ's mode_playing branch

Changes based on ChoiZ's mode_playing branch

Station: media.dir now overrides media.m3u if both are specified and non-blank
Station: Noted media.m3u and media.dir options as depreciated (uses them if present for smooth upgrade path)
Station: Combine media.m3u and media.dir options into one new media.source option
Station: media.source is now checked to see if it's a file or folder at load time, and playlist or folder list mode is selected automatically
Core: Updated to reflect new source setting when using station autocreation

Signed-off-by: achbed <github@achbed.org>