[core] Add SASL auth capability

This starts IRCv3 compatibility, but the interfaces should be refined
somewhat.
Merge branch 'master' into ircv3
[rss] Report malformed XML; skip updating feed with unchanged etag

- Throw a debug message if the feed parser detects non-well-formed XML.
- Don't update the feed in the database if the etag and modified time
have not changed.
Merge pull request #319 from saltire/rss

[rss] Report malformed XML; skip updating feed with unchanged etag
[docs] Touch up a few flaws in the documentation
[rss] Add a class for representing feed rows.

- rss._RssFeed eases accessing the row fields.
[rss] Add handling for 301 and 410 http responses.
Merge branch 'master' of https://github.com/embolalia/willie
Revert "Add trigger.raw and fix issue #310"

This reverts commit b408543071842bf04346fb7f569eaa4d1061cb13.
[coretasks] Attempt to rejoin registered-only channels
forgot to import time
Merge pull request #320 from bui/master

Revert b408543 and fix #310
[reddit] fix error when poster has been deleted

Fixes #323
Merge branch 'ircv3'
[core] Fix NameError and simplify code.
[core] Remove unblockable from commands in coretasks.

Unblockable was meant for functions that keep track of events.
[rss] Give an error at setup if DB isn't working

This will, at the lease, help diagnose #322