Update all cc code using .clang-format; please do so as well for future PRs
etc.; emacs has a handy 'clang-format' mode to make this automatic.
For comparing old changes with git blame, we can disregard this one using
--ignore-rev
(see https://www.moxio.com/blog/43/ignoring-bulk-change-commits-with-git-blame )
reimplement the old mu-log.[ch] into mu-logging.{cc,hh}
If available (and using an appropriately equipped glib), log to the
systemd journal
Only g_criticals have stderr output, all the other g_* go to the log
file / journal.
Instead of using ~/.mu, use the XDG Base Directory Specification, typically:
~/.cache/xapian
~/.cache/mu.log
~/.cache/parts
~/.config/bookmarks
Update dependencies, documentation.
Dirk-Jan C. Binnema