Enable subpixel options in Freetype
Finally nailed subpixel text rendering.

Finished allowing integer advance widths, and it is beautiful.

One of the most important fixes I have made here is that the
UV coordinates of the glyphs were wrong.
Also, due to the changes in the freetype flags, we no longer
need to clobber the horizontal hinting by rendering
to a widened glyph. This ends up giving us perfect pixel-wide
stems.
Also, changed glyph texture sampling to point (it was linear).
At 7 taps for each pixel, I really don't think we need linear
interpolation. I can't tell the difference visually.