More small improvements to DAG Editor

Improvements:
- stream name input bounces in inspector when user tries to dblclick the stream label
- better-organized less file
- fix for [MLHR-1405](https://malhar.atlassian.net/browse/MLHR-1405), handling connectionMoved
- style fixes to compatible downstream input ports when dragging connector out of output port
- slight change in generated names
- added "no settable properties" message in operator inspector
- improvements to source and sinks listing in stream inspector
- general inspector improvements
- selected port label styling
- help blocks for port attributes, stream locality
- dag canvas margin