Rewrite docstrings to facilitate API reference generation

[alexhroom]

cf. RascalSoftware/RAT-Docs#1 ; if API reference is autogenerated, then some kind of docstring formatting convention should be used to improve the way it is formatted in the documentation. This can be in the RST docstring style, or the Numpy or Google style (and we can then use the Sphinx extension napoleon to convert)

[StephenNneji]

We have agreed to use the numpy style to be consistent with Python API and RasCAL

[StephenNneji]

The user facing functions should be priority for docstring refactoring. This should help keep track of what's left and who is doing what

• RAT.API.projectClass.backgroundsClass
• RAT.API.projectClass.baseContrasts
• RAT.API.projectClass.contrastsClass
• RAT.API.projectClass.customFileClass
• RAT.API.projectClass.dataClass
• RAT.API.projectClass.domainContrastsClass
• RAT.API.projectClass.domainsClass
• RAT.API.projectClass.layersClass
• RAT.API.projectClass.multiTypeTable
• RAT.API.projectClass.parametersClass
• RAT.API.projectClass.projectClass
• RAT.API.projectClass.resolutionsClass
• RAT.API.projectClass.tableUtilities
• RAT.API.createProject
• RAT.API.RAT
• RAT.API.RATMain
• RAT.API.controlsClass
• RAT.API.enums
• RAT.targetFunctions.reflectivityCalculation