Added code to automatically connect to a 'OpenXC'-previxed bluetooth device iff one is not specified.
If bluetooth device is automatically connected, the mac address of that device is written to the shared preferences.
Modified to look for 'OpenXC-VI-' rather than simply 'OpenXC' prefix.
Clarify trace file settings.

Fixed #94.
Merge branch 'next' into pr/93
Replace tabs with 4 spaces.
Remove trailing whitespace.
Add an "Automatic" entry to BT device selection preference.