* account management rework: Personal Settings functionality
* email, password, username update
* email updates now also mails the old address for confirmation
* redo page render following the logic of:
Response ─┬─> TextResponse ─> TextResponseImpl
└─> TemplateResponse ─> TemplateResponseImpl
* split up giant files, one per response path
* caching becomes a trait, implemented where necessary
* TextResponses (Ajax) can now be cached
* make use of previously defined php classes for js objects
* Tabs, Listview, Tooltip, Announcement, Markup, Book, ...
* \Aowow\Template\PageTemplate is the new class to be cached
* do not discard error messages generated after vars have been sent to template
and store in session for display at a later time
* implement tracking consent management
* move logic out of template into their respective endpoints
