Store disc data in an intermediate object

This allows us to free the underlying (C-)DiscId object earlier.

Signed-off-by: Sebastian Ramacher <sebastian+dev@ramacher.at>
Add some more documentation

Signed-off-by: Sebastian Ramacher <sebastian+dev@ramacher.at>
Merge branch 'master' into feature/toc

Conflicts:
	libdiscid/_discid.pyx
Add toc to libdiscid.DiscId

Also handle the extraction of TOC string from the submission URL there.

Signed-off-by: Sebastian Ramacher <sebastian+dev@ramacher.at>