This makes it more readable. Unfortunately, the alternate row colors
don't apply to the row headers. QHeaderView is supposed to support
QBackgroundRole but there's a long pending bug on the Qt side for the
same - https://bugreports.qt.io/browse/QTBUG-31804
* Enable button only when one or more port is selected
* Reorder the button to make it first in the stats group
* Show some helpful text instead of a blank window when no stream stats
are available
- Automatic full column selection
- Enable/Disable toolbar buttons based on selection
- Code refactoring to avoid unncessary selectedColumns computation
PortStats and StreamStats Windows are presented as a tabbed widget.
Multiple StreamStats windows are titled to include an id to hint at the
sequence in which they were opened