Actually, the current default zoom level is fine for the linear scale.
But since the logarithmic scale is enabled by default, the default zoom
level should be adapted to the logarithmic scale.
A proper fix would be to have a comparable size for both types of scale,
but that may prove difficult to implement.
Each Babel router announces a set of prefixes (through "redistribute"
statements), which we call originated prefixes. This patch displays these
prefixes, as seen by the currently selected router.
Note that for each different selected router, we might see different sets
of originated prefixes, because of prefix filtering performed by various