test: Extend Scribe testing to encompass a complete game

Including the formation of several large-ish glyph shapes.

There's not actually a _lot_ of functional testing here. It would be
much more useful if the server reported whether a move generated a
glyph or not, (and then the test suite could verify that result on
every single move).

For that, we'll also want to aloow sub-tests that don't generate an
entire line of output, but instead just a single letter.