PolConvert is implemented as a CASA task and may be installed
as described in src/INSTALL.  The machinations at this level
are needed to integrate it into a standard DiFX build process.

Prerequisites:
- define DIFXCASAPATH enviroment, which should point to the
  bin directory of your CASA installation
- the code must be built with some care on the version of the
  numpy package which has to be the same as the one used by
  CASA.  The virtualenv package may be used to make this happen:

   virtualenv --extra-search-dir=/path-to-CASA/lib/python2.7 \
     --python=python ENV

  where ENV is some directory that will hold an installation
  of python, e.g. /opt/CASA/casa-release/lib/python2.7.  Then
  install the correct version of numpy

   source shell-fragment-to-put-CASA-at-head-of-path
   source ENV/bin/activate
   # python is a symbolic link to the casa executable
   npv=`python -c 'import numpy as np ; print np.__version__'`
   python -m pip install numpy==$npv
   source setup-difx.bash

The installed directory contains the elements needed to use
polconvert from within CASA.  Typically you might add the
following line to your .casa/init.py file to use them:

try:
    from os import environ
    execfile(environ['DIFXROOT'] + '/share/polconvert/mytasks.py')
except:
    print 'unable to load $DIFXROOT/share/polconvert/mytasks.py'

(or similar).  Create .casa/init.py if it does not exist.

You can then run polconvert directly from within CASA following
the sample input commands provided in (src/PP/)README.POLCONVERT
which should be installed in $DIFX_ROOT/share/polconvert.  You
should only do this if you are an expert....

Otherwise, you can run prepolconvert.py and drivepolconvert.py for
production processing.  See ^/sites/Haystack/ehtc/Readme-Cycle5.txt
for the EHT processing as an example.

This code has not yet been generalized for other applications, but
that should happen soon.  Really.

eof