Sync with oc project.
This supports better authorization
handling for DAP requests, especially redirection
based authorization. I also added a new test case
ncdap_tests/testauth.sh.

Specifically, suppose I have a netrc file /tmp/netrc
containing this.
    machine uat.urs.earthdata.nasa.gov login xxxxxx password yyyyyy
Also suppose I have a .ocrc file containing these lines
    HTTP.COOKIEJAR=/tmp/cookies
    HTTP.NETRC=/tmp/netrc
Assume that .ocrc is in the local directory or HOME.

Then this command should work (assuming a valid login and password).
    ncdump -h "https://54.86.135.31/opendap/data/nc/fnoc1.nc"