Markers extension: major refactoring, see details
Markers extension: major refactoring, see details

* The extension now extends Tour prototype with a #getMarkers method for
  selecting the spot markers
* (de)highlighting hooks moved to tour#start and tour#stop instead of
  guide-scope
* tests for marker visibility applicability are now delegated to
  Marker#canShow
* Fixed a bug that was causing sibling placed markers to be visible on
  creation
* Got rid of the deferring of showing tour markers on tour start
* No longer hooks into Tour#refresh
* Repositioning of markers on resize is now restricted to :overlay
  placed ones

Markers:

* Option: noClone: will not cause containers to be clones of the spot
  element but instead use a plain div
* [INCOMPLETE] Option: smart: marker will now test whether it fits in
  the viewport in its specified position, and if it doesn't will attempt to
  re-position
* Wrapping functionality broken into #wrap, #unwrap, and #isWrapped

amireh/guide.js,amireh/guide.js