Also make phantom point delta-X adjustment.
Also make print-glyph-points require Freetype version >= 2.5, which is
the latest version, at the time of writing.
R=bsiegert
CC=golang-dev, remyoudompheng
https://codereview.appspot.com/18370043
Also add a test that freetype-go derives the same glyph points as
the C freetype implementation.
R=bsiegert
CC=golang-dev
https://codereview.appspot.com/12670046