title: list of all variable names from a NetCDF dataset, in R
body: <p>I'm using the RNetCDF package in R.
  I'm trying to get a list of all variables 
  names from an imported .nc datasets (I can 
  easily get the vector of values from the 
  few variables whose names I know, but I only 
  know a small subset of all the variables names).</p>