Find data transformer (DeepLabCut#1776)

* Stricter search of analyzed data
* Edit data file suffix

DLC 2.2.0.6

check for empty default track method

DLC v2.2.0.4 release (DeepLabCut#1632)

* Standardized imread

* autoformatting

* Formatting

* Updated demo loading and modelcomparison

* Updated demo loading and modelcomparison and corr. testscripts

DLC v2.2.0.3

gitignore update

Merge branch 'master' of https://github.com/DeepLabCut/DeepLabCut

Fix GUI crash

Black coding style