Fix to read.ncdfFlowSet: pd is now initialised before being referenced.
This would lead to the following error when calling read.ncdFlowSet:

Error in sampleNames(pd) :
  error in evaluating the argument 'object' in selecting a method for
  function 'sampleNames': Error: object 'pd' not found
Merge pull request #26 from pontikos/trunk

Fix to read.ncdfFlowSet: pd is now initialised before being referenced.