[glibmm] Non-fast-forward update to branch wip/dboles/ustring_format_fold_and_test

[Daniel Boles <dboles src gnome org>]

The branch 'wip/dboles/ustring_format_fold_and_test' was changed in a way that was not a fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  36c73b9... tests/glibmm_ustring_format: Test subst & iomanips

Commits added to the branch:

  a485da1... tests/glibmm_ustring_format: Test output, iomanips