Merge tag '2.2.3' into develop

House keeping release
Merge tag '2.2.4' into develop

Content class markup clean
Add apply_filters for content, main and sub wrapper html. Allow filtering of markup via funtions
Revised content, main and sub wrappers to utilise actions with filters *within* them
Hook Plugin action hooks to theme Template functions
Bump version. Update changelog
Merge branch 'release/2.3.0'