When the search is case sensitive, g_utf8_normalize() is not called, so
the skip_decomp argument of the function forward_chars_with_skipping()
must be FALSE.
To verify that, when searching "éb", the count parameter of
forward_chars_with_skipping() have a different value:
- case sensitive: count = 2
- case insensitive: count = 3 (g_utf8_normalize() has been called)
The commit adds unit tests that didn't pass before, and that now pass
(without known regression, obviously).
https://bugzilla.gnome.org/show_bug.cgi?id=702977
The function must return TRUE only if there is a tag toggle _after_ the
iter, not _at_ the iter. So for the end iter, the function must always
return FALSE.
Add also unit tests for gtk_text_iter_forward_to_tag_toggle().
https://bugzilla.gnome.org/show_bug.cgi?id=691266
