refs #8371. Extend and refactor inputs.

Extend checking for roi and db inputs. Refactor validation and setting of inputs out into separate methods where possible to separate from future processing logic.
refs #8371. toLam functionality implemented.

Start work on toLam functionality using convert_to_wavlength.py as guide. Only the detector side of things has been implemented thus far, but test coverage is quite good, and I have implemented the pieces that mean that detector id ranges can be used.
refs #8371. Handle detectors and monitors in toLam.

Extend tests and functionality to handle monitor conversion and flat background correction.