set autoclear to false, add render and resize callbacks
added jquery.freepano.poi.js
updated jquery.freepano.js

* panorama.renderer.parameters are the object constructor parameters,
* panorama.renderer.properties are extending the object instance
* use panorama.callback for all events (panorama[event.type](event) will be called)
* renamed panorama.render to panorama.renderFrame, because of panorama.callback('render');
updated jquery.freepano.widget.js

* follow freepano core convention for callback
* hook to panorama_callback so that widget.on_panorama_<eventType>() is called, if any
* minor fixes
updated jquery.freepano.widget.hs, minor change
fix issue https://github.com/FoxelSA/freepano/issues/4