corgenelength: Normalize gene mutation scores by gene length.
In mararie/SAMBAR: Subtyping Agglomerated Mutations By Annotation Relations

Normalize gene mutation scores by gene length.

1	corgenelength(x, cagenes, exonsize, ...)

`x`	Mutation data, in the format of a matrix, including the number of mutations for samples (rows) and genes (columns).
`cagenes`	A vector of genes, for example of cancer-associated genes. This will be used to subset the gene-level mutation data to.
`exonsize`	A vector of gene lengths. This will be used to normalize the gene mutation scores.