Test and refactor cpd fmax2p cp3

[j-emberton]

This PR attempts to develop tests, modularise and conversion to Python for the cpdFmax2pCp3.m matlab function.

Work to date:

• Developed tests for cpdFmax2pCp3
• Modularised cpdFmax2pCp3
• Converted all modularised code to python
• Partial implementation to tests for function sub modules

Work to do:

• Complete matlab tests
• Integrate python code into test framework
• Debug

[j-emberton]

Sorry, just realised this is separate for a rebase!

Edit. No my bad, I was merging into wrong branch

[dorchard]

• We discussed that we don't need to worry about interpolating over NaN here because that does not occur in the (hard coded) data we are interpolating over.
• Note [[ min NaN 1 ]] Python != [[ min NaN 1 ]] Matlab - There might be more direct translations to some numpy.