Make sure that UpdateLocker is used correctly in the future
add short git hash to name of devel disk images to get different names for devel versions without manual intervention
Document Buffer::preview()
Fix memory error detected by valgrind

The assignment name = sub.str(1) reads from the first argument given to
regex_match(), but previously this was a temporary object which was already
out of scope. This did probably not matter much in practice, but invoked
undefined behaviour, and as we all know this is allowed ton format your hard
disk or kill to your cat, so better fix this.
Do nothing if converting to the same type of Note

The advantage is that the buffer will no longer be
marked as dirty when converting to the same type.

A quick break here is done instead of disabling the
LFUN because disabling the LFUN would lead to a greyed out
entry, which might confuse users. In the future, we might
want to have a radio button for switching between notes.
Add diagnostic messages for enchant spell checker dictionary requests
Add lookup for standard location of hunspell dictionaries of Debian packages