large scanning engine changes; 1.8X speed improvement, but please test stability

Hi all,

the last week I've rewritten some parts of the syntax scanning engine
(for the details: instead of inserting GtkTextMark's for all found
results, we now just store the offset, and update all offsets after each
insert or delete signal).

The results are very good, an average 1.8X speed improvement.

However, the changes are quite big, especially considering that we are
working towards a 2.0 release. So please test the latest svn checkouts
and see if the scanning is always functional and if the stability is good.

regards,
	Olivier