gplugin/gplugin

Implement enable switch in GTK4 viewer

2021-12-16, Elliott Sales de Andrade
f03eee6f9596
Implement enable switch in GTK4 viewer

This adds a `state-set` signal on the plugin row, which merely re-broadcasts the signal from the switch. This enables the view to watch for the signal and pass along the desired state to the manager.

The plugin row sets the display of the enable switch whenever the plugin state refreshes. I'm not entirely sure if all states are displayed in the way we want.

Testing Done:
Start viewer and see that auto-loaded plugins are actually enabled, and that others can be enabled/disabled.

Reviewed at https://reviews.imfreedom.org/r/1193/
# Dependencies
GPlugin depends on the following at a bare minimum:
* glib-2.0 >= 2.40.0
* gobject-introspection, libgirepository1.0-dev
* meson >= 0.42.0
* gettext
* help2man
* a C compiler
A full build (enabled by default) depends on the following:
* gtk-3
* python3-dev, python-gi-dev, python3-gi
* libperl-dev, libglib-perl, libglib-object-introspection-perl
* liblua5.1-0-dev, lua-lgi
* valac
All of these packages and their development headers need to be installed
prior to building GPlugin.
# Building
GPlugin uses [meson](https://mesonbuild.com/) as its build system. As such
compiling is a little bit different than your typical `./configure`, `make`,
`sudo make install`.
Meson requires you to build in a separate directory than your source. As such,
these instructions use a separate build directory.
To compile you need to run the following commands:
```
meson build
cd build
ninja install
```
If you want/need to tweak the build system (to enable/disable certain loaders)
you can do so at any time by using `meson configure` in the build directory.