Add updated Dimant-Oppenheim files

[chocnaut]

This PR adds an updated Dimant-Oppenheim model file, a new array types file, and a plotting test script.

Changes included:

• Updates [original DO file updated] "src/metablate/models/dimant_oppenheim_2017.py"
• Adds [new array types file] "src/metablate/array_types.py"
• Adds [plot file] "src/metablate/dimant_oppenheim_plottest.py"
• Removes [old array types file] "src/metablate/types.py" file

Notes:

• Lots of cleaning to do

[chocnaut]

A recent change has been added to this PR:

• Adds a solver function to find r from the electron density morphology

Note:

• Still needs some cleaning