We know the preference is never empty, so stop testing for this. But
don't maintain two different preferences with basically the same
content. Instead add the '/git' suffix where needed and keep this all in
one place.
Simplify the extraction of the branch name from the cloud URL.
Also a typo fix and a new comment.
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
These were declared in pref.h and defined in subsurfacestartup.c.
pref.c didn't even exist. Create it and move preferences-related
structs and functions there.
setup_system_prefs() is left in subsurfacestartup.c, since it
works with environment variables.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>