Summary: Test files for being lexicographical sorted

Description:
This checks if the lines of files or filehandles are monotonically and
lexicographically increasing, (= are already sorted). It may consume less
RAM and be faster than the naive way of doing 'cmp myfile.txt <(LC_ALL=C
sort myfile.txt)' and it runs at O(n) instead of O(n*log(n)) time and keeps
O(1) lines instead of O(n).

$checker->is_filehandle_sorted({fh => $input_fh, id => "my-file.txt"});
Checks if $input_fh is sorted - throws an exception if it is not sorted
and returns true if it is.

$checker->is_file_sorted({path => "/path/to/file.txt", id =>
"my-file.txt"});
Checks if the file at path is sorted - throws an exception if it is not
sorted and returns true if it is.

Maintainer: nobody