Improvements to one page report

- 0% transport counts removed from report header
- Transport types are now dynamic based on static vector
  - which transports (ethertypes) appear in the header more easily changed
  - added vlan as a type since we don't handle it
- time histogram x label handles short captures more gracefully
  - Uses (<1 second) rather than being blank
- added visibility color chips for short port bars
  - If a colored port histogram bar is too small to be seen, a chip of the
    color is rendered immediately below the bar
  - added != operator for rgb_t
    - evidently this is the first time I've tried to use != rather than == for
      rgb_t