Configure pre-commit and address flake8 issues

I am learning more about the package. Thanks for the maintaining the package.

Following the instructions under CONTRIBUTORS.md, I tried running pre-commit using pre-commit run --all-files. I am seeing a bit of flake8 errors below:

py4DSTEM/visualize/overlay.py:1152:5: F841 local variable 'N' is assigned to but never used
py4DSTEM/visualize/overlay.py:1187:80: E501 line too long (92 > 79 characters)
py4DSTEM/visualize/overlay.py:1222:80: E501 line too long (80 > 79 characters)
...
py4DSTEM/visualize/show.py:107:80: E501 line too long (83 > 79 characters)
py4DSTEM/visualize/show.py:108:80: E501 line too long (97 > 79 characters)
py4DSTEM/visualize/show.py:109:80: E501 line too long (88 > 79 characters)
...

Other minor errors:

py4DSTEM/utils/configuration_checker.py:461: atributes ==> attributes
py4DSTEM/utils/configuration_checker.py:463: libaries ==> libraries
py4DSTEM/utils/configuration_checker.py:484: conditons ==> conditions
py4DSTEM/utils/configuration_checker.py:559: requriements ==> requirements
py4DSTEM/utils/configuration_checker.py:559: additonal ==> additional

Would you be planning on implementing pre-commit? It could be perhaps integrated at the PR level.

Start with CONTRIBUTORS.md and run pre-commit run --all-files to reproduce the reported findings. Review py4DSTEM/visualize/overlay.py, py4DSTEM/visualize/show.py, and py4DSTEM/utils/configuration_checker.py; done means the reported flake8 errors and listed spelling errors are addressed and pre-commit can be integrated at the PR level.