Bugfixes and improvements

This commit fixes the few known remaining issues with woodchuck and makes some improvements.

- Added 19px and 38px logos
- Rework all logos to have transparent background
- In a multi-person thread, look up the first email that isn't the mailbox owner
- Fix timing issues that cause events to be ignored
- Fix syntax in viewport.js
- Add options page and address bar icon (right-click to set options)
- Allow user to set hostname in plugin options