[Dvipng] FreeType render modes

[Tobias Wolf]

Salve, 
I’ve seen some results from other renderers which show that some of
Freetypes modes can improve legibility of LaTeX.

I've determined that HINT_MODE_AUTOHINT_LIGHT and FT_LCD_FILTER_DEFAULT
are a good combination. Light autohinting because it does not affect
horizontal advances, only horizontal lines like =, -, _, or T, E.
LCD mode gives better Latin Modern and other Type1 fonts.

Have you considered offering these modes? There is a small tool that can
use all the modes here:
http://cvs.savannah.gnu.org/viewvc/ft2demos/src/ftdiff.c?revision=1.12&root=freetype&view=markup

Of course the images need to be RGB. 16 gray levels don’t work
obviously.

Regards,
Tobias