Add rawhdr command line utility and a callable function

[Richard Elkins]

rawhdr FILEPATH - command line utility to print all of the guppi header fields.

blimpy.rawhdr.get_obsnchan(FILEPATH) - callable function to retrieve the number of observation (coarse) channels.

[david-macmahon]

FWIW, I put this bash function definition in my ~/.bash_aliases file:

function rawhd()
{
  /usr/bin/fold ${1:?usage: rawhd RAW_DATASET [PATTERN]} | sed '/^END /q' | grep "$2" | sed 's/ *$//'
}