Properly track channel permissions on join

Update requirements

Fix deprecation warning of imp import

 # Fixed

- Multiple versions of a plugin could run simultaneously if Cardinal
  experienced a disconnection (#195)
- ticker plugin no longer triggers on holidays -- thanks
  @ForeverEndeavor! (#194)
- github plugin correctly recognizes pull request URLs
- dice plugin had no limits which could result in memory exhaustion

Add WeatherAPI.com weather provider

# Added

- Twitter URL handling plugin
- imgur URL handling plugin
- random plugin (dice rolling)
- `.tell` command to `seen` plugin for messaging offline users
- `.search` command for searching IMDb (returns multiple results which
  can be selected)

# Changed
- Ability to change
- `ticker` plugin attempts to be more resilient to missing API data
- Generic URL handling can now be disabled in the `urls` plugin (it will
  only rely on other plugins to handle URLs)

Release v3.2.0

- Added Wolfram Alpha plugin
- Added movies (OMDb/IMDb) and TV (TVmaze) plugins

- Urban Dictionary plugin now shows upvotes and downvotes
- "Natural language" syntax to Cardinal now requires full command syntax (`Cardinal: ping` -> `Cardinal: .ping`) and supports `@regex` commands
- Weather plugin now uses km/h abbreviation instead of kph
- Plugins can now use `entrypoint = PluginClass` instead of defining a `setup()` function which is now deprecated (#186)

- `setup()` function in lieu of new `entrypoint` module attribute (#186)

- Plugins which raised an Exception from their constructor were not able to be reloaded
- Urban Dictionary, Github, Youtube, and Last.fm plugins now `deferToThread` their HTTP calls, improving performance
- sed plugin now handles empty replacement patterns (e.g. `s/foobar//`)
- Wikipedia plugin now handles various edge cases, such as disambiguation pages, better (#185)
- Edge cases around event callback registration, particularly when wrapped in `@defer.inlineCallbacks`

Fix some Wikipedia edge cases (closes #185)

- Disambiguation cases are now plainly stated as such
- Pages that have a banner followed by an empty <p> tag now correctly
  find the first non-empty <p> tag.
- URLs are now listed as the URL Wikipedia redirected us to, rather than
  the naive URL we attempted
- Failures to find a Wikipedia page with a space in the name now show
  the original name requested rather than the underscored version.

Add tests for is_action and parse_action in util

Add ability to issue raw commands on connect (closes #120)