Introducing tagged-timelines with moodle-items.

Fixes:
- tags are not sorted alphabetically in tagged-timeline
- rendering of moodle-items without timestamps

Features:
- tagged timelines include moodle-items (for logged in users)
- moodle security-key can be added in user-settings

Known issues:
- personal timelines do not include moodle-items yet
- MathJax-Rendering fails after upvote/or tagging in result_view
- when submitting a new post in profile view, history get's out of sync
- wrap lower toolbar into a div (in note-timeline-view)
- improve add-tag dialog (in note-timeline-view)
- consolidate styling of links (hrefs) and buttons (clicks)
- tag-filter-view, login-menu and user-menu still interfere
  (if screen-width is not so wide needs revision)
- Fix adding multi-paged (a.k.a. very long) notes in timeline-view
- move more edit-related functions into a more private scope
- commit changes from here also into the ck-mathjax repository

Note:
This should be working with DeepaMehta 4.1.3 but was just tested with 4.2-SNAPSHOT.