* [MRG] Create a new figure and test each plot type #127
- move `plot()` to `plotting.py` as `plot_pdf()`
- modify plotting functions to return matplotlib figures
- add `test_plotting.py` and baseline images
- import `plot_pdf()` in `__init__`
- update `cli.py` to use `plot_pdf()`
- update advanced usage docs to reflect changes
* Change matplotlib backend for image comparison tests
* Update plotting and tests
- use matplotlib rectangle instead of `cv2.rectangle` in
`plot_contour()`
- set matplotlib backend in `tests/__init__`
- update contour plot baseline image
- update `test_plotting` with more checks
* Update plot tests and config
- remove unnecessary asserts
- update setup.cfg and makefile with `--mpl`
* Add to
* Add tolerance
* remove text from baseline plots
update plot tests with `remove_text`
* Change method name, update docs and add pep8
* Update docs
Add fix for coverage
Add source and omit to coveragerc
Update coveragerc
Update coveragerc
Add source to coveragerc
Update coveragerc source
Add init to tests
Fix ImportError
Fix ImportError again