import pipe from dplyr and not magrittr

[MarcinKosinski]

This 1-liner https://github.com/MI2DataLab/factorMerger/blob/master/R/factorMergerClasses.R#L6 drives the final user to install an extra package. There is no point to import pipe operator from the extra package when you have one in the dplyr. Less dependencies, the better. Just remove this line, after you fully import dplyr.

magrittr is a sophisticated tool to be used when one is familiar with extract , extract2, multiple_by , add equals , not or many more functions. If those are not in the need, just don't anticipate anyone to install extra software. Less dependencies, less problems in the future with the reproducible research.

CC @durszlaczek