[meta-issue] Network-specific stuff

[progval]

Currently, Limnoria supports lots of channel-specific data, but channels with the same name on different networks are considered the same.

This issue tracks the status of each of these migrations.

• [x] config values: #252, PR: #1367

  • done
  • backward-compatible + forward-compatible

• [ ] capabilities: #1179

  • probably backward-compatible, not forward-compatible

• [ ] plugin databases: #1368

  • probably backward-compatible, not forward-compatible

• [ ] ircdb: #1453