[XeTeX] Macro for kerning adjustment

[Arthur Reutenauer]

> I'd prefer to stick with Gentium, if these manual kerning issues can
> be automated by some additional lines in the preamble or in some other
> typesetting configuration file.

  What you want to do is roughly equivalent to editing the font, except
that you would use TeX commands instead of font properties, so it seems
pretty safe to assume that you would need a lot more than “some
additional lines” to implement this.  You would have to care for the
accurate placement of each diacritic mark over each base character, and
that is not the kind of thing you want to automate.

  Of course, in your case you're only interested in a few composite
characters, and it could probably be done within a reasonable amount of
time; but, generally speaking, it's better done upstream by the font
designer.  So it is usually best to choose a font that already have the
correct glyph positioning tables.

	Arthur