Many improvements thanks to Daniel Scott!
* Added alpha_transparency option & tests
* Fixed syntax in Readme
* Fix default value in docstring
* Added alpha_transparency argument & tests for all relevant plots
* Added pytest github workflow
* Fix pytest yaml syntax
* Added miniconda pandas to github workflow so that test suite can run
* Added requirements to pytest
* Removed explicit reference to tests
* Removed macosx support from tests. Colormap not supported on osx"
* Removed explicit reference to tests
* Moved tests dir
* Initialized test directory
* Added wget to dependencies
* Improved commenting in test coverage
* pytest fix for slow CI on windows
* pytest fix for slow CI on windows (contd)
* Added numpy installation to conda
* pytest fix for slow CI builds
* Disable testing for windows (only linux)