bump to 3.4
revert to --backtrace enabled by default, since the original goal of this change was addressed in other ways
Revert "bump to 3.4"

This reverts commit ad7ab8f09afe1eac025a6da87a45c83ada15544d.
updated .po files from waf i18n, plus an updated gtk2_ardour/de.po from Edgar Aichinger