Add dragEvents map for dojo adapter.
Added log messages to parts of dojo-adapter that may not be working yet.

Turned off try-catch error handlers in jsPlumbUtil.wrap to aid debugging.
It would be good to have a jsPlumb debug flag to turn things like this on/off.

initDraggable is now attaching the drag callback to dojo/dnd/onMove.
However, the callback is showing a number of errors, possibly due to the
fact that the callback is now being given a dojo/dnd mover object as an
argument.

Still need to work on initDroppable.
Got dragging almost working, but coordinates are off and
stopping the drag goes haywire.
Need further tweaks to getUIPosition(...).
Merge branch 'master' into bvds
Undo some logging.