Add support for imposm importer

[andypl78]

Hi,
There is a new and efficient importer for Openstreetmap.
There are currently stable version imposm2 but I tested an early version of imposm3 written in the GO and it is very fast compared to the importer osm2pgsql and imposm2.
It might be worthwhile to implement this instead of Tirex + osm2pgsql?
Regards

[miurahr]

It is worth trying. Targeted next release.