We cannot compile app as a whole on MS Windows yet, but with those changes it is now possible to compile and run our new video sink alone on Windows OS
Install plugin lib stuff into a dir named "clapper-1.0" instead of "clapper-0.0". Even through our API is still very unstable, we cannot go down with versioning. The sink importers being installed there are not part of public API anyway.
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.
Ship custom gtk4glsink plugin as part of API insead of normal gstreamer plugin. This avoids gstreamer plugin registry conflicts with gtk3 plugin and allows more customization.
