Support for bilingual documents

[hcayless]

This will require changes in Leiden+ as well. We have several documents that are properly bilingual, i.e. they don't just have a word or phrase in a different language (for which <foreign> is appropriate), but have, e.g. both Arabic and Greek sections. This would be better dealt with by <ab xml:lang="grc">, <ab xml:lang="ar"> for blocks of text, or <seg xml:lang="grc"> for inline sections.

[jcowey]

At present the xml:lang is encoded as attribute of div

<div xml:lang="grc" type="edition" xml:space="preserve"><ab>

Would this now look like

<div type="edition" xml:space="preserve"><ab xml:lang="grc">

For all texts or just those that are properly biliingual?

Adding Leiden+ syntax will be required to accompany this.