Record hyphens from Minikin and draw them

This patch plumbs up hyphens computed in Minikin's LineBreaker,
records them in a new column in StaticLayout, and draws them.
DynamicLayout mirrors the new column, and TextLine is also changed to
make sure the hyphen is only drawn for the last run in a line.

There is a rather primitive mechanism for loading hyphenation
patterns, for testing only at this point.

Change-Id: Ib208568c0f6cff12cf834047500ec1da9ea9f430