Drawing vertical text glyphs

[Miklos Vajna]

Hi Lubos,

One catch I noticed while working on the opengl text render / BTLR text
direction for Writer is that the rotation angle of text and verticalness
seems to be two different things.

The rotation angle is obvious, but once you rotate rotate "to the
right", latin text simply rotates all glyphs, while (as I understand)
Asian text typically just transforms the center of those glyphs and the
glyphs themselves are rendered un-rotated. I think the idea is that
vertical=true means this "don't rotate at glyph level" mode.

At least that's what I remember from core.git commit
f7453b956bcf83ec13c805d243f20cb209289179.

Hope this helps,

Miklos