Reifying Tags still uses the old Advanced Editor

Summary: When I go to an undefined Tag, and press the "Edit" button, it reifies that Tag, turning it into a real Thing. This should use the Thing Editor, but instead uses the old Advanced Editor.

The reason for this is mainly that we have no easy mechanism to both create a Thing with doCreateThing2() and set Properties in it, and we want to set the Display Name. Ideally, in TagThing we would set PageHeaderProperty to a customized version, which would use a parameterized version of _createInstanceLink() that set the Display Name as part of the Link.

In order to make this work properly, we first need to prove that you can pass initial properties to doCreateThing2(), then create a variant of _createInstanceLink() that appends initial property values to the link.