Issue #90: Move to direct-call framework design ...

Rather than signalling events everywhere and letting extension plugins
handle them if they choose to, the framework should be reworked to
directly call functions on the appropriate integration plugin. This will
both reduce overhead from events and simplify plugin work by removing if
statements at the beginning of every event handler.

This will require follow-on changes to all source integration plugins to
work with the new parent class API.

Version bump in Source plugin to signify API changes.

Fix #28: Updated copyrights from '20081 to '2008-2009'

Fix #13: Convert project license to AGPL3.

Added form security tokens to repo/management pages.

Wider repo update page.

Moved core Source plugin to plugin_lang_get() usage.

Initial Public Offering.