Add new GStreamer plugin with custom video sink for Clapper video player.
The main difference is that unlike the old one, this does not operate using `GtkGLArea`
anymore, but processes and displays `GdkTextures` directly through `GtkPicture` widget.
Also this one is installed like any other GStreamer plugin, thus can be used via
`gst-launch-1.0` binary or even by other GTK4 apps if they wish to integrate it.
In order to not depend on GL stuff at build time, this plugin uses seperate GModules
called "importers" in order to import different kind of memories into GdkTexture. This
allows expanding its capabilities further then we were able to do before.
Add missing PiP icons from web devel kit. Also add play/pause
icons at the right size and remove all workarounds/scaling
implemented or these two.
Playback icons are always two bars for pause and triangle for play,
so hopefully this will not be problematic, as this guaranties the
right size for them that Adwaita unfortunately cannot provide.
The "clapper_src" directory name was unusual. This was done to make it work as a widget for other apps. Now that this functionality got removed it can be named simply "src" as recommended by guidelines.
This seemed like a good idea when the app still used GTK3, but GTK4 already has a built-in video widget. Maintaning this single functionality would be hard and I cannot promise a stable API anyway. The app main and only purpose will be a video player from now on.
Default "GLib.log_structured" method is painfully slow and time provided by it is not very accurate. It also slows down program execution even when G_MESSAGES_DEBUG env is not set. Use custom debug scripts for faster and more accurate messages logging instead.
