Handle locally-installed-OSes the same way that online-OSes are handled
i.e. unique only by name, and only add if newer. Fixes #106
Also includes a fix to not show duplicate OS entries if the version
on the SD card is newer than the version available online.
Force FAT partition labels to uppercase, fixes #140
And in case of conflicts, start the numeric 'suffixes' at 1 instead of 0,
and allow more than 10 partitions with the same label (by appending 2-digit
suffixes if necessary).
If a partition label is too long, resize it instead of clearing it.