Oh, one other minor thing -- this should be a shouldPreventCycles() implementation in the new EdgeType class. Otherwise, users can create T1 -> T2 -> T1, etc., which messes a few things up a bit. I'll just fix that in the pull.

Oh, and in doing "edited blocking task(s)", these feed strings are slightly off.

The reason there are different "transaction" and "feed" strings is that the "transaction" strings are shown on the object, so the edited object is implicit (e.g., alincoln edited this object.). The "feed" strings are shown elsewhere (normally, in feed) so the edited object is not implicit and must be explicit (alincoln edited T123: foobar). If the object is excluded, the affected object isn't clear in the feed story:

Specifically, the viewer can't tell which task relationships were edited for unless the object is included in the string.