Add new GStreamer plugin that consists of multiple elements 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 used by other GTK4 apps if they wish to integrate it.
This commit adds new video sink that uses a new kind of memory as input, called
`ClapperGdkMemory`. With it comes a simple dedicated memory allocator, buffer pool
and a `clapperimport` element that converts system mapped memory frames into
`GdkTextures` that are later passed in our `ClapperGdkMemory` for the sink to display.
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.
