Structural problems with code

[timcallow]

atoMEC currently relies on the config.py module to store various global variables. This worked ok for the initial purpose of the code, which was basically just set up to solve the KS-DFT equations for an average-atom model.

However, it's becoming clear to me that this a major problem when one wants to use the code in a modular way as more functionality is added, particularly post-processing tools for a given output of a KS calculation. Such issues are not limited to just the config.py module, some classes are initialized in such a way that it is not possible (without great difficulty) for a user to create their own instances, rather they only work if created via a KS-DFT calculation.

Fixing this issue will require a significant reformulation of the code... But needs to be done!