User-visible changes:
- Fixed a crash related to making keyboard visible.
- Better fallback: when selecting a missing layout named "fr+foo", "fr" will be used instead.
- When enabling the keyboard manually, it will never be stuck in the numbers view.
- Thai layout
- US-Colemak layout
- Czech layouts
- Esperanto layout
- Bulgarian layout
- Improved Norwegian layout

That's a lot of new layouts!

Plus a bunch of stricter warnings, MIPS64el support, and reproducible building.

visibility: Stop calling GTK functions from the visibility manager

See merge request Librem5/squeekboard!425

The viibility manager state is changed from various handlers, which are not guaranteed to be reentrant, most notably the Wayland handler for preedit done.
As the state is changed, relevant requests to synchronize user-visible UI are fired from the same handler.

In case of imservice_handle_done, GTK widget show function was being called, which triggered another round of handling Wayland, leading to the done handler being called again, and flaking out.

To solve this, the phase of issuing commands needs to be separate from adjusting desired state. It seems that the easiest solution is to delay the show() and hide() calls into the next GTK main loop spin.

A better solution would probably inject itself directly after the change of desired state, so that *all* the side effects are delayed.

Farsi/Persian keyboard layout

See merge request Librem5/squeekboard!424

Make layout lists more ordered

See merge request Librem5/squeekboard!417

dbus: Reset hints if text input missing

Closes #256

See merge request Librem5/squeekboard!421

no: Use wide button switching between numbers, symbols and base

See merge request Librem5/squeekboard!419

Contributors have started to make it messy.

Bulgarian language keyboard layout

See merge request Librem5/squeekboard!418

build: Enable unused warnings in C

See merge request Librem5/squeekboard!375

Fixed by Dorota Czaplejewicz <dorota.czaplejewicz@puri.sm>

Better fallbacks

See merge request Librem5/squeekboard!415

Central visibility policy

See merge request Librem5/squeekboard!409

Reproducible build

See merge request Librem5/squeekboard!413

The goal is to be free of unused X class of problems. For this, CI and any "serious" builds will fail on warnings. Debug builds, used in development, will warn by default but not fail.

In addition, the 'strict' build option is added for when the debug build should fail on unused warnings as well.

Added US Colemak Keyboard Layout

See merge request Librem5/squeekboard!403

Add Czech keyboard layouts

See merge request Librem5/squeekboard!414

Altered from original to take reproducibility into account. Not tested on mips64el.

Mipsel compat

See merge request Librem5/squeekboard!412

Two variants:

* Czech Standard (= qwertz)

* Czech qwerty

The accented letters layout corresponds to the UCW [1] layout shipped
with xkb, so we follow this precedent.

Like the DE layout, and unlike the US layout, the CZ layout has a
comma key and a narrower space bar. The added comma key also serves as
a visual balance to the added accents key, to keep the spacebar
centered.

The layouts have been tested manually on PinePhone.

[1] https://github.com/xkbcommon/libxkbcommon/blob/c60b77ea512bef92e481be38972b58dd71a34180/test/data/symbols/cz#L180