Lots of diagonal bits of large type pieces

Lots of diagonal bits of large type pieces

This is essentially all of them apart from the W and M pieces.  There
turn out to be obvious places to have the diagonals cross character-cell
boundaries such that they should all join up.  Whether this gives and
aesthetically tolerable outcome, I'm not so sure.

The W and M pieces are a bit confusing, because they're meant to span
two character cells vertically, but the obvious design doesn't.