Additions to trac

This trac uses (so far) two custom plugins:

• trac+bzr, a massively hacked up version of trac-bzr allowing us to access bzr through the source browser. Code is in http://bzr.pkgcore.org/marienz/trac+bzr/.
• trac-rst, allowing slightly prettier access to our documentation than through the source browser, while still keeping it under version control and available offline. Code is in http://bzr.pkgcore.org/marienz/trac-rst/. Name is misleading: it can show documentation in any format supported by trac's mimeview system. Uses trac's versioncontrol api to get at the files instead of accessing them or the versioncontrol system directly, so it should work with svn or other non-bzr tracs too.