An introspection fix & a Gtk3 test

[Zach Morgan <zpmorgan gmail com>]

Hello, list!

I've made a couple changes that I'd like to propagate to your gnome
repositories. The issue was that TextIter's find_char methods weren't
working because Introspection couldn't handle the unicode character
type.

https://github.com/zpmorgan/perl-Gtk3/commit/101fba260d99e3ef1270278e3fa332de2957be24
https://github.com/zpmorgan/gi/commit/fcf90564255c9b870cea9fc2daa0c118091eaaaa

If anyone's interested, this is for a transcription playback editor
I'm working on. https://github.com/zpmorgan/wordbath

Gtk3 & GStreamer bindings are super, as always. CSS theming in
particular has worked better than I expected.

Thanks,
Zach Morgan