In line with [MPoL #223](https://github.com/MPoL-dev/MPoL/issues/223), change base spatial frequency unit in codebase from [klambda] to [lambda]. I think it's only needed in `process.py`, as of now.
In line with MPoL #223, change base spatial frequency unit in codebase from [klambda] to [lambda]. I think it's only needed in
process.py, as of now.