critbit89 - A crit-bit tree implementation for strings in C89

This implementation closely follows the original CWEB source by Dan Bernstein [http://cr.yp.to/critbit.html], provided as generated C code at [https://github.com/agl/critbit]. It was converted to human-readable C89 code, and should be more portable than the original version. Additionally, support for custom memory allocators has been added.

Hereby placed under public domain, just like Dan Bernstein's original implementation.