Document changes and release 0.20.0
We've got some stuff merged for a while that haven't reached users yet. Let's get them out.
[ Tobias ]
* Update README.md - Hint to the control file for dependencies.
* Update meson.build - Added 'motorola,osprey.ini' to install_data.
[ Sebastian Krzyszkowiak ]
* zbar: Use GDK_SELECTION_CLIPBOARD instead of PRIMARY
[ Chris Talbot ]
* QR Code: use g_uri_is_valid() to determine if there is a valid url
[ Pavel Machek ]
* fix comment and printf formatting
* fix PinePhone support