Log Message:
Update to 5.13, provided by the author and maintainer.
changes since bozohttpd 5.12:
        o  support .mp3 files (type audio/mpeg)
        o  use stat() to find out if something is a directory, for -X mode
changes since bozohttpd 5.11:
        o  constification
        o  fixes & enhancements for directory index mode (-X)