add new classes page_type and filter modules WIP

• the page_type controls all the different outputs like
	– home overview
	– events and event detail
	– documents
	– links
	– and news texts
• the filter module checks for the classes page_type
	– adds the classes virtual navigation items
	– adds the class detail subpage navigation items if any content exists
Merge branch 'master' of github.com:/rapila/plugin-schulcms