#49 Use SAX to check XML dependencies during repo init

[Mike Brown]

(formerly a bug report)

The 4Suite repo install utilities handle dependencies
between, say stylesheets and their imports. In this
way, it arranges to load files into the repo according
to dependency needs. The same is handled on export.

This intelligence is not implemented very well for
XML/DTD relationships and external entities.

Mike Olson and Uche discussed a likely solution. Right
now all the dependency checking is done by parsing
and using ad-hoc XPath. We propose to replace this
with one SAX pass on all XML files which gathers
external entity references (and XIncludes?) for the
dependency listing.

(Note that this would probably be complicated by the
use of Catalogs)