Fix Averaging and Conformational Analysis for Protein Multimers

[skfegan]

Summary

This is to fix issue #161 where a protein tetramer gave a Value Error with an inhomogenous shape for the conformational states array.

Changes

Change 1

• replaced two instances of the .append function with the .extend function where arrays were being combined

Change 2

• fixed a typo in one if statement

Change 3

• added one paragraph to the documentation to explain the grouping argument and the available options for it.

Impact

• The code can now use the averaging for molecules large enough to have dihedral angles and different conformations.
• The calculation of dihedral angles and conformational states is now not skipped for the residue level.
• Improved documentation so users can understand how to get the type of averaging that they want.

[harryswift01]

Thanks for spotting and fixing this, it looks like we now correctly handle averaging for larger molecules and no longer skip dihedral and conformational calculations at the residue level. I also appreciate the addition of the documentation and updated tests. Happy for this to be merged into main.