talkatu/talkatu

Remove a bunch of incomplete widgets instead of porting them to GTK4

TalkatuMenuToolButton and TalkatuToolDrawer were mean to be used to mimic the
condensed format bar that is in Pidgin 2, but it never worked right and we'll
probably revisit the toolbar in the near future.

TalkatuMessageActions was intended to be used as an anchor widget in the
history when the history was still GtkTextView based. Now that the history is
based on GtkListBox this is no longer necessary.

Testing Done:
This was originally built against the default branch where it was compiled without any warning/errors and passed the unit tests.

Reviewed at https://reviews.imfreedom.org/r/1237/
# Talkatu
![logo](logo.png)
[ ![Issues](https://img.shields.io/badge/Issues-YouTrack-ee3b8b.svg) ](https://issues.imfreedom.org/issues/TALKATU)
Talkatu is a collection of Gtk+ widgets that are useful for chat applications.
It was started as a rewrite of the GtkIMHTML widget found in Pidgin, but
quickly expanded to include most things related to conversation windows.
This is highly experimental right now and might eat babies, we're not sure
yet. So proceed with caution :-D
## Name
The name is a pun of talkatoo from Super Mario Odyssey which just so happens
to also say "talk at u" :-D
## Dependencies
Currently Talkatu depends on
* glib-2.0 >= 2.40.0
* gtk+-3.0 >= 3.10.0
* gladeui-2.0 >= 3.0.0
* gspell-1 >= 1.2
* gumbo >= 0.10
* libcmark
## Internationalization
All of our internationalization work is done via the
[Talkatu](https://www.transifex.com/pidgin/talkatu/dashboard/) project under
the [Pidgin organization](https://www.transifex.com/pidgin/) on
[Transifex](https://www.transifex.com). If you would like to contribute
that's the place to do it.