Previously we were only passing this information on the debug dialog
when debugging warnings and criticals. Now it will also have the
information for crashes, hence recommending people to update their GIMP
instead of reporting bugs on old versions.
Instead of making the focus on bug reporting, the debug dialog will now
make the focus on updating the application if it is found that one is
not using the last version.
Debug data (backtraces and co.) will still be available and copiable,
but under an expander, and bug report button won't be displayed (i.e.
data will still be available upon request but we don't push anymore
people to submit it directly if they are using old versions of GIMP).
Of course, if you are using the last version (or version check was not
possible), the dialog still stays the same.
Move gimp-debug-tools.c from tools/ to a new app-tools/ subdir,
which should contain external tools needed by app/, and which is
built *after* app/ (unlinke tools/). This allows gimp-debug-tool
to depend on libapp and libappwidgets, instead of on actual source
files from app/. Building sources from app/ in another subdir
screws with the distclean rules, and breaks distcheck.