Canonical pre-verse Psalm titles are being filtered out

Canonical pre-verse Psalm titles are being filtered out (like Psalm 10 in SynodalProt). Although the canonical title itself has canonical=true, the parent pre-verse div (which was created by osis2mod) doesn't carry the canonical attribute (and it currently cannot because theoretically it could contain both canonical and non-canonical titles).

The problem seems to be with the osisheadings.cpp filter which ignores title canonical attributes when such a title appears inside a pre-verse div.

A simple patch for this is attached, which is what xulsword is using. With the simple patch, if ever canonical and non-canonical titles were to appear together within a single pre-verse div, then neither would be filtered. But this is better than filtering out anything canonical, all the time.

It seems the complete fix would require an overhaul of osisheadings.cpp or else require a change to osi2mod to insure that it never mixes canonical and non-canonical titles together in any pre-verse div.