#67: Upgrade Range Widget 

Upgraded the range widget as follows:
 -Added a reset method which unsets the ranges of the widget, when the
ranges are unset the widget selection nodes are no longer active.
 -The widget is initalized and reset to the min,max, selectedMin,
selectedMax being NaN.
 -Double click on the widget resizes the selected range to 100%
Merge branch 'master' of https://github.com/diirt/cs-studio-integration.git into diirt-master