Ahh

- Added ext.lon360() which converts west longitudes to east
- Added "maxmin" and "w2e" inputs to ext.get_idc()
- Added "directory" input to pre.wget_fi()
- Added "interval" input to vis.plot()
- Fixed bug where xlabel and ylabel wasn't set for single plot

- Added easily accessible docstrings.py for easier referencing
- Linked the docstrings.py in README.md
- Reorganized README.md for better logical progression
- Added requirements to setup.py

- Added new package: pre.py
- New functions pre.py: wget_fi() and concat_nc()
- Renamed ext.eval() to ext.ahh()
- Function ext.ahh() no longer has unnest=True as default
- Added "bare" input to ext.ahh
- Enhanced ext.read_nc() to include more options
- Enhanced vis.plot() to include exception handling notices
- Removed "name" input in vis.plot() and changed "save" input
- New function in vis.py: global_map
- New function in sci.py: get_norm_anom
- Aesthetic changes all over
- Complies with Flake8 and Codacy

- Creation of ahh with vis, sci, and ext packages.