Lint test - check all params in nextflow.config are mentioned in main.nf

[ewels]

Sometimes parameters are added in nextflow.config and then removed from the pipeline. These dangling parameters confuse matters as they need to be in the schema and clutter things up. However, they are quite difficult to spot when reviewing.

It would be nice to have a simple test that checks that all params are found in main.nf. May need one or two exceptions, but that's fine.