Adding tis620.2533-0 into Thai Pango engine

[Chookij Vanatham <chookij vanatham eng sun com>]

Hi Owen, Robert,

In Solaris, we bought Thai TrueType fonts from Monotype and we are using the
exact Thai font layout which has been using in Thai MS window. Even we use
the exact layout but we don't do the same clustering (display cell). We use
the rule of clustering (display cell) from Wtt2.0 standard (from NECTEC).
I'm figuring out where I should add the code in Thai pango engine so that
it can be run on Solaris and having Wtt2.0 rule clustering (cell).

I run into one question that might be related to the design of Pango but
not specific to Thai.

If different platforms use the same "charset" name, ie, tis620.2529-1, and
idividual platform wants to have its own clustering rule, would that be
possible ?

or another word,

if Solaris wants to have its own clustering rule which is different than what
it has in other platform for tis620.2529-1, would that be possible to do
that ?

Chookij V.