DUI: top result highlight for the second time

This PR should be merged after [that one](https://github.com/Benglin/Dynamo/pull/156).
Top result should be highlighted after every data update.

Reviewers
@Benglin ,@vmoyseenko, please take a look.

Link to YouTrack:
[MAGN-4851](http://adsk-oss.myjetbrains.com/youtrack/issue/MAGN-4851) DUI: Top result should be highlighted by default (no tooltip) and should add the node when pressing enter