This makes metadata work again on ICY servers.

Fixes: #2310

Thanks to Bernd Geiser <bg@ferncast.de> for initial report.

Fixes: #2309

Fixes: #1946

That was easy.

Thanks to Jörg Krause to pointing this out.

Fixes: #2307

This is based on a patch by Stephan Jauernick <info@stephan-jauernick.de>

This corrects the order of the search paths for includes and
fixes a possible FTBFS.

Thanks to Joshua Root for reporting and providing a patch.

Fixes: #2306

from Icecast.

and add a few constants for tag IDs we'll need soon.

(Fixed signs in the EBML parse helpers.)

so that processing code can use it.

The plugin currently allocates & deallocates the state,
but otherwise does not use it.

Fixes: #2299