2D Shape Descriptors

Implement Fourier Shape Descriptors and variants. see for example: https://scholar.google.de/scholar?hl=de&q=Review+of+shape+representation+and+description+techniques%2C+Zhang%2C+2004&btnG=&lr=

Start with the issue and the linked Zhang 2004 review of shape representation and description techniques. Use the review to determine which Fourier Shape Descriptors and variants are in scope, then inspect the repository for the appropriate integration point. Done means the agreed descriptors and variants are implemented and covered by suitable verification.

Written by the indexing model from the issue text.