Enhanced the .twit command significantly...

* Get past tweets (n tweets ago; 1 = current): `.twit aplusk 3`
* Get tweet by ID: `.twit 381982018927853568`
* Match on Twitter URL in chat and fetch tweet
* Show URL for fetched tweet at end of message
Merge pull request #16 from ramsey/twit-updates

Enhanced the .twit command significantly
[twit] Fix double '@' with .twitinfo
[twit] New link to the Twitter API website
Merge pull request #18 from iceTwy/master

Fix double '@' with .twitinfo & new link to Twitter API website
[twit] No matter the count of '@', display only one '@' in .twitinfo
Merge pull request #19 from iceTwy/master

[twit] No matter the count of '@', display only one '@' in .twitinfo