[Fontconfig] Changing to hintslight globally by default + hintfull for otfs

[Nikolaus Waxweiler]

> Not  really. speaking of changing constant name and attributes
> mainly, given that we changed something around this, users still
> doesn't know what is the best choice even though how those looks
> better may be subjective. just thought it may be helpful to provide
> configuration files per font format as examples with more detailed
> comments rather than changing/adding something for people only who
> knows technical thing in fonts so that they can learn what's better
> for their env after that. that said, it comes up from the name of
> FT_LOAD_TARGET_XXX somewhat and still behaves differently with the
> same flags among font formats as you mentioned, it might be better
> changing in FreeType first if you like.

Okay, so would like to see:
- 10-ttf-hintnative-xy.conf
- 10-ttf-hintauto-yonly.conf
- 10-ttf-hintnone.conf
- 10-otf-hintnative-yonly.conf
- 10-otf-hintauto-yonly.conf
- 10-otf-hintnone.conf
- 10-pfab-hintnative-???.conf
- 10-pfab-hintauto-yonly.conf
- 10-pfab-hintnone.conf
including comments that explain what's going on and why? Will look into it.

I'm note sure about FT's API, I guess it's set in stone until FreeType 
3. I'll just start with the above confs ;)

> I don't have any objections for changing the default hintstyle in
> fontconfig personally otherwise. as I wrote earlier, the improvements
> are welcome.

:)

 From the above list, I'd recommend setting
- 10-ttf-hintauto-yonly.conf
- 10-otf-hintnative-yonly.conf
- 10-pfab-hintauto-yonly.conf
as the default active configurations. As soon as I have written them :D