Mutational signatures

[Nicklas Nordborg]

See ​https://cancer.sanger.ac.uk/signatures/

We should implement the different signature that are described here:

• For WGS variant calling: SBS, DBS and ID
• For WGS structural variant calls: SV
• For Copy number: CN
• For RNAseq: RNA SBS

We already have the SBS signature implemented as part of the WGS variant calling pipeline (but there seems to be a bug so the results should not be trusted!).

We should get rid of the current implementation and instead create a new step in the pipelines that create new child items to the variant call items (for example MutationalSignature). For each pipeline the relevant data files and a plot for the signatures should be created.