Deprecate CodeAndRoll2::rowMedians in favor of matrixStats::rowMedians

[vertesy]

The goal here is to use the probably much better written matrix stats function. But we have to preserve the functionality Therefore, the call should be matrixStats::rowMedians(mat, na.rm = TRUE).

Could you please open an issue in codeandroll2?

I think we should depreciate that implementation of row medians with Immediate warning message, Explicitly Calling the user to use matrixStats::rowMedians(mat, na.rm = TRUE). You can create a PR there immediately, that will be even better.