Tracker: Avoid bogus warning for Exposure_LOW

Thanks to CJ Davies on the mailing list for reporting.
New utility: psmove_dfu_mode

Thanks to Alexander for researching the magic numbers.
Various compiler warning fixes
Prefer local filenames to filenames in the data directory
Merge branch 'cmake-patches'
Merge branch 'check-errors'
Merge branch 'debian-packaging'
Merge branch 'divide-by-zero'