* All 3 icons are combined into a single row instead of 3 separate rows
* Tooltip to clarify meaning of icons
* Qt Model-View displays icon left-aligned, so use a custom delegate to
center-align it
* Add a icon for "Transmit On"
* Edit icons for "Start/Stop Capture"
bps stats are derived from the Bps stats and represent line rate taking
into account the per packet overhead on the line with the following
assumptions -
* Link type is Ethernet
* Bps (and total Bytes) stats don't include the 4-byte FCS
Fixes#241
