Changes:
- Change art behavior in album list, video list, and playQ list
- Change track number format to #.
- Support pad's external SD card and USB storage
- Move "show unrated songs" option to star threshold dialog
- Fix album forced low resolution album art in play view bug
- Fix video tab or file f/c or ANR bug
- Fix bitmap memory leak f/c bug
- Remove "video playlist", integrated into playQ.
- Remove "audiobook tab", integrated into playQ.
- Remove "Rapid Browser", which is a workaround for really old Android and devices.
