Import functions for Medtronic CGM

[brinnaebent]

Would like importmedtronic(filename) for importing and formatting of Medtronic CGM. Need: data file from Medtronic CGM.
To do:

• Reach out to Medtronic to get sample CGM file for testing

• Build function importmedtronic(filename)

• Test importmedtronic() function with other functions and test file

• Update package and re-release on PyPI

• Update user guide instructions