Fix the warnings for methylation data

[markziemann]

Shouldn't be a warning, maybe a message instead.

 gu_lim_m <- mitch_import(gu_lim,DEtype="limma",geneTable=gt,geneIDcol="Name")

The input is a single dataframe; one contrast only. Converting
        it to a list for you.
Note: Mean no. genes in input = 790658
Note: no. genes in output = 22269
Warning message:
In mitch_import(gu_lim, DEtype = "limma", geneTable = gt, geneIDcol = "Name") :
  Warning: less than half of the input genes are also in the
        output