Support releases with multiple catalog numbers

[CommandMC]

MusicBrainz releases can have multiple catalog numbers. This patch adds support for showing more than the first one, which can be important information (imagine you're ripping a disc with many releases and checking the catalog number to rule out any that don't apply)

One potential issue with this is the %C disc/track template, which now joins catalog numbers with , . I'm not sure if the , character is restricted on NTFS/Windows. On the other hand, I'm not sure which character to substitute it with, or whether keeping the current behavior (using the first catalog number) in that case would be what the user expects