Vertex Phasors Class

[willGraham01]

Continues #63 |

VertexPhasors class

Along similar lines to #205, breaks out extraction of the phasors at the user-specified vertices into its own class. This reduces the number of auxiliary functions defined in iterator.cpp, moving the relevant methods into this class and adapting the syntax accordingly.

The ComplexAmplitudeSample class previously that previously handled the data storage has been absorbed into the VertexPhasors class, and hence no longer appears in the codebase. Previously, this class was one of those in arrays.h for data storage only.

Fieldsample class-breakout

Breaks out FieldSample class into it's own source and header file, since it can now handle the "fieldsample extraction" portion of iterator.cpp internally, within it's own class.

Reason for the file-breakout:

• arrays.{h,cpp} should contain only basic data containers and related methods. Objects with their own header/source are those that are interacting with other fields, classes etc that we have defined in fields.h or arrays.h.
• arrays.{h,cpp} is a huge file of declarations and definitions, and adding complex functionality in admist all that is going to come back and bite us if we keep going like this. Might create some more subfolders in src if we end up breaking out a lot of files like this.

Other minor things in this PR

• test_FieldSample.cpp has been moved out of the array_tests testing subfolder since it's no longer part of arrays.h.
• test_ComplexAmplitudeSample.cpp has been repurposed into test_VertexPhasors.cpp.
• test_interpolation_determination.cpp was missing a spdlog:: string.

[samcunliffe]

LGTM.

My only really comment: I wonder if we should have an abstract Phasors class. Can you factor out any common functionality? Does it buy us anything?