[atlas] More even earth distribution of measurement probes

On Fri, Mar 10, 2017 at 11:47:12AM +0300,
 Marat Khalili <mkh at rqc.ru> wrote 
 a message of 94 lines which said:

> 300 probes, expecting them to cover most world countries.

Most people seem to expect some sort of random selection in the
complete set of probes, but it does not work that way. Some probes are
favored over others (anchors, for instance) and there is a priority
for the less loaded probes.

> Wouldn't it be nice to have the following features in web-interface and API:
> * even distribution of probes by country or continent based on
> population, area, and other user-defined weight numbers; * avoiding
> probes with same ASNs

Currently, you have to do it yourself: retrieve the list of probes,
apply your criteria, and submit a measurement with the explicit IDs.

> Without direct access to probes database

But you have access
ftp://ftp.ripe.net/ripe/atlas/probes/archive/2017/03/