Maintain history state object when changing pages

This is required for history-management libraries like jquery-pjax which uses the state object to load pages via AJAX.
Merge pull request #169 from longzheng/patch-1

Maintain history state object when changing pages
Code style improvements
no longer caching $itemsContainer + reinitialize method (fixes #153)
really destroy instance on destroy method (fixes #160)
reworked binding and unbinding
replaced deprecated size() with .length (fixes #162)
Merge pull request #171 from fieg/ajax

Ajax improvements and more
Merge pull request #1 from webcreate/master

Merge webcreate master