Plane summaries

[LouisDesdoigts]

Implements a series of updates:

nd_pixel_positions: A generalisation of the pixel position and coordinate functions

• Rebuild the functions in utils/coordaintes.py to merge all of the pixel positions and coordinate functions into a single nd-version
• Updates the corresponding code base to use this new method

plane-summaries: Adds a series of summary and plotting method designed to help examining of the big systems to help with debugging.

• Adds a general cartesian and angular unit conversion method to be used in the summary and plotting methods
• Adds display and summary method to all Spectra, Sources, Optics and Detector classes
• Adds plot and summarise methods to the core classes

[LouisDesdoigts]

Also expands the unit conversion functions in utils/units.py