Improved the interface for editing tasks: you can now add a comment at
the same time as you edit a task. I backported the util::word_diff
proc to project manager. I use it to show the difference between old
and new descriptions of tasks. I'll also use it to show differences on
the revisions of tasks (not done yet). I backported it so that
project-manager won't require acs-kernel 5.2; later, we'll move to the
correct util::word_diff. There are certainly a few bugs in how
descriptions are displayed: I haven't got the mime-type settings right
yet, but it's close. The email notifications that go out are much more
informative now.
