Avoid some compiler warnings
Startup: Show check errors on stderr

In case the UI is crashing at first use somehow, as it currently seems to
be on Fedora.
Startup: Do not crash when reporting check problems.

* glom/main.c: Instantiate the Application earlier, to ensure
  that GTK+ is ready for use.
  Also call gtk_init() explicitly because Gtk::Application needs
  a fix for this anyway, and it would be nice to use this fix
  in Glom versions that do not need a newer gtkmm.

  Bug #680411 (Bjørn Lie, Dominique Leuenberger)
Move to a generated (in dist) ChangeLog

I still do not like not being able to correct the commit messages
and I still do not like how it leads us to be lazy when writing
the ChangeLog entries, but git still makes it hard to manage
branches when using a manually-written ChangeLog.