RAW 2.2.1 released

[jesse.b...@gmail.com]

I'm pleased to announce the release of RAW version 2.2.1. 

Installation links are available here:

https://bioxtas-raw.readthedocs.io/en/latest/install.html

This version contains a single bug fix:

• Fixed a bug that prevented some calibration and masking operations from being used.
  

Because this bug prevented the use of major features it warranted a quick fix.

All changes:

• Fixed a bug that prevented some calibration and masking operations from being used when running with newer versions of matplotlib (including the prebuilt installers).