dragfeature handler -- drop geometry over another.

[crschmidt]

When you have a polygon feature over a point feature in the same layer, and you attempt to drag the point feature, you get errors about this.feature.geometry being undefined.

[crschmidt]

The problem is more specific than this: the actual problem is when you drag a geometry, *drop* it on another one, then without leaving the bounds of that geometry, try to drag again.

dropping it unsets the feature in doneDragging... but really, I think that we should only remove the feature in outFeature, since we're originally setting it in overFeature.

For the record, doing this also gets rid of the really-annoying flickr when dragging points in the modifyFeature control, so I think I'm on the right track here.

[crschmidt]

tests pass in FF - needs to be run in FF, but i expect they'll work there

[crschmidt]

Of course, the comment meant 'needs to be run in IE'

[tschaub]

Thanks for catching this Chris. I think this must have crept up with changes to the drag handler (or some other). All looks good, and tests pass in IE. Please commit.

[crschmidt]

(In [4341]) When you have a polygon feature over a point feature in the same layer, and you attempt to drag the point feature, you get errors about this.feature.geometry being undefined. Fix this by not unsetting this.feature inside the doneDragging. (Closes #971)