issue #11 Add callbackError to click2dial(), to report more errors back
Issue #11 Add "Call" buttons to Thunderbird address book

This allows to call the phone numbers that the user keeps
in his Thunderbird address book, by clicking a button
directly next to the phone number.

This is hooking up both the contact overview in the
main AB window as well as the contact edit dialog.
However, only the latter works at the moment, see comments.
issue #11 Fix card overview update
tested with current Thunderbird trunk
allow re-use under MPL in other extensions or Mozilla code
Merge pull request #19 from benbucksch/master

Thunderbird address book integration