reimplement and improve several vis elements, refactor

- show brighter country outlines the more peers are online there
- fix country tooltips' display of country.bytesEver and country.bps, was
  erroneously using bpsUp, bpsDn, bytesUp, and bytesDn
- don't show 0 bps connection arcs
- move connectionOpacityScale logic to directive
- ditch CONFIG