Rebase tree.
Too many changes...
IE fixes, HTML fixes, ++
Tune caching functionality a bit.
Always prepend /
Flush only in parent process.
Show empty results for specific search.
Add usage functionality to Xapian module.
Rework usage stats.
Avoid spurious commits.
Remove cruft.
Improve flushing logic,
Speed up include file handling.
Since reference_file adds all symbols anyway, don't bother looking them up.  Just strip the reserved identifiers.
Make phys_path persistent over object lifetime
Make usage indexing changes effective, update progress bar display, ++
Whitespace cleanup.
These are also cached in PgBatch.
Sacrifice database integrity constraints for performance.  The lxr datastore is mostly write-once as far as the individual tuples are concerned, and the foreign key reference can really hurt performance on large bulk insertions into big tables.
Store caches as preallocated plain-string buffers, to avoid the overhead and unpleasant memory allocation patterns that arrays entail.