timeline: Add custom parser for "markers"
timeline: Add custom parser for "markers"

It should be possible to define markers in ClutterScript when
describing a ClutterTimeline.

The syntax is a trivial:

  "markers" : [
    { "name", <marker-name>, "time" : <msecs> }
  ]

While at it, we should document it inside the API reference, as well
as fleshing out the ClutterTimeline description.

ebassi/clutter,GNOME/clutter,kerrickstaley/clutter-vala,heysion/clutter-clone,djdeath/clutter-android,GNOME/clutter,Distrotech/clutter,djdeath/clutter,GNOME/clutter,djdeath/clutter-multithreaded,GNOME/clutter,collects/clutter,djdeath/clutter-android,Distrotech/clutter,djdeath/clutter,Distrotech/clutter,collects/clutter,djdeath/clutter,jigpu/clutter,collects/clutter,djdeath/clutter-multithreaded,Distrotech/clutter,kerrickstaley/clutter-vala,collects/clutter,djdeath/clutter-multithreaded,djdeath/clutter-android,djdeath/clutter-android,kerrickstaley/clutter-vala,Distrotech/clutter,Distrotech/clutter,jigpu/clutter,djdeath/clutter,heysion/clutter-clone,collects/clutter,GNOME/clutter,ebassi/clutter,heysion/clutter-clone,jigpu/clutter,djdeath/clutter,jigpu/clutter,djdeath/clutter,djdeath/clutter-multithreaded,ebassi/clutter,jigpu/clutter,djdeath/clutter-android,ebassi/clutter,heysion/clutter-clone,jigpu/clutter,ebassi/clutter,kerrickstaley/clutter-vala,heysion/clutter-clone