Circular spatial query filter parameters for eidaws-stationlite

[damb]

This one falls into a similar category as #14.

At the time being, for fdsnws-station requests only rectangular spatial query filter parameters are resolved by means of eidaws-stationlite while circular spatial query filter parameters aren't.

As an optimization and in order to avoid broadcast requests across all EIDA including all stream epochs, resolve spatial query filter parameters at eidaws-stationlite, as well. This includes:

• latitude | lat
• longitude | lon
• minradius
• maxradius

Note that circular spatial query filter parameters are optional w.r.t. fdsnws-station (see https://www.fdsn.org/webservices/fdsnws-station-1.1.pdf). However, they are provided by most of EIDA's fdsnws-station endpoint implementations.

Thanks for reporting, @jfclinton.