Add a display title to groups of bands

[johnpauls]

Currently each band has a display name such as "0-50 meters" or "50-100 meters" However there is a not a good way to have names for group of bands together such as "0-100 meters" when both are used. This should be added with the assumption that the bands are added from the center out - that is if you have 3 bands you need a name for 1 +2 and 1+2+3 but you don't need names for bands 2 and 3 together or bands 1 and 3 together. This is particularly important for networks with an unlimited distance band like 100 + meters.

See NCRN/BirdViz#45