Modified S10setup to move userdata to sdcard on boot if /xbmc-data directory exists on sdcard

Mount mSD card as sync, slightly slower write speeds in favor of data integrity.
first partition of sdcard mounted as /mnt/sdcard
Copies all of /tmp/userdata to /mnt/sdcard/xbmc-data/userdata if /xbmc-data directory exists on sdcard
Then bind mounts userdata from sdcard over locations on filesystem to xbmc uses sdcard instead of internal storage.

also........
-Dropbear
Modify S50dropbear to get keys from sdcard if they exist.
With this modification, if you copy your ssh keys from /etc to /media/sdcard/xbmc-data/etc dropbear will use those on boot.
Nice little benefit of not having to clear your cached keys everytime you upgrade firmware.
Make xbmc-data directory so not case sensitive

Document a few variables
Have dropbear put SSH server keys in /tmp/userdata/etc/dropbear so they persist

This will cause the keys to persist across firmware updates and works regardless of whether you have data on sdcard or internal storage.
There is still a fallback, the S10setup script still makes keys in /etc/dropbear so if something is wrong with /root still will start SSH
Enable cache for copying to memory, card then disable it for safety
Add copying file splash screen

this depends on shutdown/splash patch
fix dropbear ssh key merge