make the Navigation control support pinch-zoom

[erilem]

This ticket suggest making the Navigation control support pinch-zoom by default *if* the PinchZoom constructor is defined (PinchZoom.js is included in OpenLayers.js)

See  http://osgeo-org.1803224.n2.nabble.com/PinchZoom-in-Navigation-td6289661.html for the full discussion.

[erilem]

See patch-3273-A0.diff . The Navigation.html tests pass in FF4 and IE8. Please review.

[bbinet]

We need to check that this.pinchZoom control is not null in activate and deactivate methods since the ticket abstract says: "making the Navigation control support pinch-zoom by default *if* the PinchZoom constructor is defined".

Once this is done, this should be good for commit.

[erilem]

Replying to bbinet:

We need to check that this.pinchZoom control is not null in activate and deactivate methods since the ticket abstract says: "making the Navigation control support pinch-zoom by default *if* the PinchZoom constructor is defined". Once this is done, this should be good for commit.

Thanks for the sharp eyes. Modifying the patch just now...

[erilem]

(In [11961]) make the Navigation control support pinch-zoom, r=bbinet (closes #3273)