fixes crashes due to mistakes in the merge and before: zoomer local vs. closure instance collision + broken UMD wrap
- fix: by removing (commenting out) x/y position tweaks in to() code, the element to zoom to is again properly centered in the view.

- allow the panning parameters to be configurable, among others.

- keep the options intact while you zoom in & out.

- reset() API can now also 'reset' the options, next to resetting the view.

- unify/clean the code: all places which require the window/viewport dimensions now use the same internal function getViewportSize() (which includes the IE fix that only existed for one run-time path of several before)

- unify code and bring in line with RevealJS: use 3D transform instead of 2D transform and use the internal function transformElement() for this, same as in RevealJS

- to() API now also zooms out (reset view) when passing a NULL spec/element reference.

- always apply the HTML5/CSS3 standard style last; same order of applying browser-specific attributes as RevealJS and as in general CSS best practices.

- removed the google analytics chunk from the demo: it only crashes anyway.