Version 1.6
~~~~~~~~~~~
* rjc 2019.1.4
* new -w feature to allow one difx pass of mixed-bandwidth data
* rjc 2018.9.14
* trap too many channels, add -g feature to filter for freq groups
* rjc 2018.8.10
* fixed bug in case of multiple different bandwidths
* rjc 2018.7.17
* Fixed too-many-pcal-tones bug for many tone case
* Version for DiFX-2.6, Mar 4, 2019

Version 1.5
~~~~~~~~~~~
* Added crossed auto correlations to type 1 files
* Version for DiFX-2.5, May 16, 2017

Version 1.4
~~~~~~~~~~~
* support mixed/zoom mode correlations
* support version 1 file format for pcal
* in mixed mode denote sidebands as upper for hops
* Version for DiFX-2.4, Nov 4, 2014

Version 1.3
~~~~~~~~~~~
* put data weights into type 120 record
* Version for DiFX-2.3, Dec 20, 2013

Version 1.2
~~~~~~~~~~~
* Version for DiFX-2.2, June 1, 2013

Version 1.1
~~~~~~~~~~~
* Post DiFX 2.0.1
* Version for DiFX-2.1, May 4, 2012

Version 1.0
~~~~~~~~~~~
* For DiFX 2.0.1, tagged June 12, 2011