Set 'bubbles' to true for key event.

This fixes the scroll-to-cursor hack.
I don't think this hack is required in newer versions of Firefox,
but I don't know which version fixed it.
Fixes #2
Update context finding.
Communicate with JSON instead of join/split kludge
Use async queries instead of threads
Add more tag prefixes/metatags. Fixes #6
Remove .cvsignore files
Upgrade manifest version for Chrome
Update default URIs
Do multiple request per tag update
Change label for upload URI in settings