first draft of the Timeline module

The constructor stores a reference to the player (currently only one).
Second, it parses the metadata given to form a data structure composed
of elements like the example at the top.
use timeline module in web player

The Chapter module is the first module to expect the timeline instance
as the only constructor parameter.
Chapters are gathered using `Timeline#getDataByType`.
`getMaxChapterStart` was stripped from chapter modifying code.
Merge branch '2.1.x' into timeline_abstraction

Conflicts:
	js/modules/chapter.js
removes legacy code

Using strings for chapter data has been deprecated a long
time. Just use objects instead.
enhance Timeline

Add method getter and setter for timeline currentTime. That
encapsulates player time completely.

Add method rewind that calls each registered module update methods.

Refactor Chapters.update to expect timeline object.
Call Timeline.rewind on player ended.
refactor `logCurrentTime` default timeline.update listener
Call jQuery’s trigger method on wrapped Timeline instance instead of
dispatching it to the player.
adapt ACTIVE_CHAPTER_THRESHHOLD

0.3 is too long for the third chapter in the test file to be activated.
only absolute links in examples
enhances Makefile
Merge branch 'timeline_abstraction' of github.com:line-o/podlove-web-player into timeline_abstraction
fixes setting of the time

The player now waits until it can actually set the time before trying
to do so. Also it now uses the mediaelement.js way of doing that.
fixes missing 'this'
makes the player remember the old time

The savetime module now uses the timeline instead of the player. Also,
it now sets the playtime upon init.
makes js/controls.js use the timeline for get/setting time
follow up fix
improves Makefile
simplifies deep linking code
delete the cached playtime on ended
adds progressbar module