[XeTeX] Macro for kerning adjustment

[Sven Siegmund]

> Are you strongly committed to using Gentium? The simplest solution at
>  this point would be to use a font (such as Charis SIL) that has
>  diacritic positioning support.

Well, I really like Gentium more than Charis SIL, although Gentium has
no boldface yet and misses some kerning pairs. (Also between ʧ
(U+02A7) and the ejective mark ʼ (U+02BC) I have to insert exrta space
(\hspace{0.1em}).

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. I'd comment them to find them later
and remove them when using other fonts with proper kerning.

But I'll think about Charis SIL a bit more. But I don't like its look.
It's too angular. I hope the Gentium team at SIL will release an
improved Gentium until 2010 so I'll be able to typset my thesis with
it (-:

S.