DragFeature control should trigger afterfeaturemodified

[bartvde]

In the doneDragging function the afterfeaturemodified event should be triggered on the layer, just like the ModifyFeature Control does.

[bartvde]

The same applies to the beforefeaturemodified and featuremodified events.

[bartvde]

I'll attach a patch which implements this, one omission currently is that beforefeaturemodified can not be used to cancel the modification, but this would probably require changes to the Drag Handler as well, so I could argue this deserves an additional ticket.

[bartvde]

Tests pass in FF3.6 and Safari 5, please review.

PS feel free to bump to 2.12 since this is not a regression.

[bartvde]

Not critical for 2.11 so moving to 2.12

[crschmidt]

This looks fine. Feel free to commit.

[bartvde]

In with  https://github.com/openlayers/openlayers/commit/a46489db1aedfd94dc188dd4acc1ba8e699d9321

[bartvde]

I've reverted this change since it was causing issues see #3527, se reopening and changing status to needs more work.