Get a two-digit version of the R version
Arguments
- Rversion
- Version of R (only used if - typeis not- source.) Defaults to R.version, but this can be specified as any of the following formats:- a character string with the two digit R version, e.g. "3.1" 
- a list with components - majorand- minor
- the result of - getRversion()
- the result of R.version