generate_col: Function that somehow generates a new column called...
In interzoneboy/MS-prep: MSprep does basic parsing of sieve data

Function that somehow generates a new column called "new_col_name" from the old column, called "col_name". splitFunc is a function that accepts a vector, and returns a new vector. This function is intended to do things like split sample names from the default values that are multipart and full of "_"s.

1	generate_col(d, col_name, new_col_name, splitFunc)

`d`	Input data frame needing new_col_name from col_name
`col_name`	The name of the column to use in generating the new one.
`new_col_name`	What are we going to name the new column.
`splitFunc`	Takes a single vector, returns a single vector, and contains the column creation logic.