Address 2300 — no text inside `<facsimile>` (at least, not in `<line>` or `<zone>`)

[sydb]

• Add a constraint (in Schematron) to require that there NOT be text content (other than whitespace-only text nodes, of course) inside 'zone' or 'line' elements that are themselves inside a 'facsimile' element.
• Add a test that should fail that rule to detest.xml.
• Change the expected results to match new outputs.