Introduced breadcrumb variants.
Introduced page style global variables.
Merge branch 'feature/style_improvement' into develop
Introduced subclasses of WebPageElement microdata.
Skips rendering empty page block tags.
Added Article microdata.
Simplified navigation link tags.
Merge branch 'feature/microdata_support' into develop
Ready for version 0.8.4.
Merge branch 'release/0.8.4' into develop