PanZoomService now used for linking panzoom and panzoomwidget
- Panzoomwidget no longer requires config and model to be passed to it; instead it gets these by means of the PanZoomService. Requiring them to be passed explicitly was turning into just another way of derailing stuff
- rewrote readme file to outline new way of linking stuff
- bumped version number to 1.0.0 internally (but not on git just yet)