Pycroscopy

**Updates since last release**

We have dropped support for python 2.7.


**Host of bug fixes**
* ImageWindowing function now accepts step sizes and window sizes without restrictions that were causing previous shape errors
* Fixed spectroscopic dimensions in TR-KPFM translator
* Small robustness edit to GIV translator
* Pickling error fix

**Substantial Updates**
* Added relaxation analysis and Visualization tools with new jupyter notebook
* Added a new PiFM translator

**Other Updates**
* Updated documentation for using translators
* Minimum requirement for pyUSID is now 0.0.8
* Replacement of imread from skim age with PIL/pillow

A small primarily bugfix-related update to pycroscopy. Most changes are under the hood. Briefly, this new release has:

- Translator updates: Changes to trKPFM translator to add additional dimensions, several bugfixes
- A variety of small bug fixes
- Added method 'is_valid_file' to most routine translators
- Fixes and updates to examples in the documentation
- Edits to PiFM Translator and addition of a bandpass filter class to processing/fft

* pycroscopy no longer implicitly imports pyUSID for legacy reasons
* GIV Bayesian inference, SignalFilter classes now can scale to multiple computers in a cluster via MPI thanks to the new pyUSID.Process class
* New GKPFM notebook
* New PiFM translator
* Updates and bug-fixes to OneView, GLineTranslator, Nanonis, Igor IBW, ImageStack translators
* Bug-fixes to BE processing notebook, Loop fitting, etc.

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