Update BlockerTest re: new on-opener handling.
Yet more Indenter revamping. Vamp vamp vamp!
Return '\n' for line.length.

Scans include that character and those should report that character as
whitespace, not as a mysterious null.
More indenter work.
find -> indexOf, added lastIndexOf(pred).

Also fixed some errors where _offset wasn't being used when searching. This
would have caused sublines to search incorrectly. Need more tests!
Give us a toString.
Report useful error message in this assert.
Yet more indenter work.

We have something pretty passable now.