HSLayers.Permalink() is a graphical component, enabeling to the user
to save current map state and pass simple url to someone else, who can open the
map exactly in the same sate, original user sees it.
Permalink (but also HSLayers.Control.State, Embeded or Compositions) uses
HSLayers.Format.State() - JSON-encoded map content.
The format can save:
- Current map zoom
- Visible layers - including layers, added by the user
- Layer transparency
- LayerSwitcher organization
- Drawed vector graphics
Permalink users StatusManager - PHP-based script, which is storing and handing
out the JSON files.