Make dialog's close button use same as tabs
Remove duplicate GET from message sending
Only allow one tab per whisper target
Fix invasion messages to comply with server
Change the way channels are stored again

This new system relies on a semi-unique tagging system to treat each
channel's metadata as part of an object. It necessitates the changing
of a large portion of code just to recreate the old functionality. The
change should leave everything as it was before with two exceptions:
* Tabs that have been closed will retain their history (and can be
  reopened)
* The <hr> used to show old chat history now show on all channels
  (including whisper channels) when joining
Small cleanup related to previous commit

- Remove some now unused variables
- Fix some things using those variables
- Fix a RegExp bug in the script tag detection
Swtich some parts to be more consistent with styles
Add <hr> to reopened tabs and new tabs
Animate tab open/close