Get the version number for proj4 as a list.

proj4 >= 5 does not play nicely for pseudocyl projections (see basemap issue 433). Checking this will allow us to raise a warning when plotting using basemap.

Returns:Package version as a list of three integers. Empty list if pyproj not installed. With option raw_string=True returns raw version string instead. The last version number can indicate different things like it being a version from the old svn trunk, the latest git repo, some release candidate version, ... If the last number cannot be converted to an integer it will be set to 0.