netcdf-c

[NCF-284]/ ZQX-155900

Some servers do not properly
implement the current DAP2 spec.
It turns out that this server is one of those:
    http://nomads.ncep.noaa.gov:9090/
When a reference such as this is made:
    http://nomads.ncep.noaa.gov:9090/dods/gens/gens20140123/gep_all_12z?prmslmsl[0][0][0][0:359]
tt is returning this:
Dataset {
    float prmslmsl[ens=1][time=1][lat=1][lon=360];
} gens%2fgens20140123%2fgep_all_12z;

when it should be returning this:
Dataset {
  Structure {
    float prmslmsl[ens=1][time=1][lat=1][lon=360];
  } prmslmsl;
} gens%2fgens20140123%2fgep_all_12z;

The reason is that when picking fields out of a grid,
one must maintain the fully qualified name, so the grid
is converted to an enclosing structure.

It turns out that the problem was that
when I create the new structure node, I was
improperly linking it into the existing graph.
This caused a null pointer failure.
Fix is to make sure the relevant field (node->root)
is set.