Provide methods to pan w/out changing zoom level

[lmonson]

I'm trying to implement my own pan controls from outside the directive. It doesn't appear that the directive exposes direct methods to pan -- the logic for a "pure pan" is embedded in mouse move event handler.

I would be very happy to provide a pull request -- but wanted to ensure I hadn't missed anything beforehand. I would augment as follows:

changeZoomLevel(newZoomLevel, clickPoint)
zoomIn(clickPoint)
zoomOut(clickPoint)
getViewPosition(modelPosition)
getModelPosition(viewPosition)
** panView(delta) // delta.x and/or delta.y

[mvindahl]

Hello lmonson,
That seems like a sensible and useful addition to the API. You are correct that the functionality does not currently exist; mainly because I designed the API as I went along and in response to the needs of a proprietary project which needed the pan zoom functionality in the first place.
I'll review the pull request ASAP. Once again thanks for your contribution :-)
Cheers,
/Martin