Issue: Can't Quote Comments

Fixed in Alpha 6.

The following has been added:
- fixed the "Reply with Quote" button to send parameters about the quoted post.
- created logic to verify quote parameters, and on-submit check that the quote was used after all
- added code to generate quote tags based on those parameters, including multi-quote (although no multi-quote feature exists)
- modified the comment DM to send alerts (e.g. in XenForo) when a quote is used
- modified subsciption delegation to skip subscriptions for users who were already alerted for this comment

Quoting other types or in other types (like pages) should be handled in a separate issue if that feature is desired. Implementing quote alerts themselves (user settings, templates, etc) is outside the scope of this issue, which was simply to fix the quote button not doing anything.