Port Pkt stats are no longer shown by default. To see them and byte
counters, use context menu option - "Show details" (renamed from the
existing "Show Byte counters")
* 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
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
