library package for gsort

 Package gsort is a library for sorting a stream of tab-delimited lines
 ([]bytes) (from a reader) using the amount of memory requested.
 .
 Instead of using a compare function as most sorts do, this accepts a
 user-defined function with signature: func(line []byte) []int where the
 []ints are used to determine ordering. For example if sorting
 on 2 columns, one of months and another of day of months, the function
 would replace "Jan" with 1 and "Feb" with 2 for the first column and
 just return the Atoi of the 2nd column.