Radixsort non-comparative sort

[seahrh]

Radixsort O(nw) will be faster than comparative sorts O(n lg n) if w < lg n.

• If n = 1K, lg n ~=10
• If n = 1M, lg n ~= 20
• If n = 1B, lg n ~= 30

Use case: sort Unix time for 2038-12-31T00:00:00 is 2177366400 (10 digits).

See https://www.unixtimestamp.com/index.php

User inputs character set and its ordering in a list.

Provide default implementation for alphanumeric case-insensitive, based on Java regex

[_,0-9,a-z]

See https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html

Interface NonComparativeSort