Doc: xml: More information about schema versioning
Refactor: xml: Work out more schema details automatically
Fix: xml: best-match.sh helper needs to be included in make dist
Refactor: xml: Autogenerate versions.rng based on RNG_versions in the makefile
Refactor: xml: Replace CRM_DTD_VERSION with a function that returns the relevant known_schemas entry
Clone the latest resources schema
Feature: xml: Support resources with requires=unfencing