mkp224o - vanity address generator for ed25519 onion services

This tool generates vanity ed25519 (hidden service version 3) onion addresses.
For context, see <https://gitweb.torproject.org/torspec.git/plain/rend-spec-v3.txt>.

REQUIREMENTS:
libsodium, GNU autoconf, GNU make, UNIX-like platform (currently tested in Linux and OpenBSD).

BUILDING:
`./autogen.sh` to generate configure script, if it's not there already.
`./configure` to generate makefile; in *BSD platforms you probably want to use
`./configure CPPFLAGS="-I/usr/local/include" LDFLAGS="-L/usr/local/lib"`.
You probably also want to pass something like "--enable-amd64-51-30k"
or "--enable-donna" to configure script for faster key generation;
run `./configure --help` to see all avaiable options.
Finally, `make` to start building (`gmake` in *BSD platforms).

USAGE:
Generator needs one of more filters to work.
It makes directory with secret/public keys and hostname
for each discovered service. By default root is current
directory, but that can be overridden with -d switch.
Use -s switch to enable printing of statistics, which may be useful
when benchmarking different ed25519 implementations on your machine.
Use -h switch to obtain all avaiable options.

CONTACT:
For bug reports/questions/whatever else, email cathugger at cock dot li.

ACKNOWLEDGEMENTS & LEGAL:
To the extent possible under law, the author(s) have dedicated all copyright and related and neighboring rights to this software to the public domain worldwide. This software is distributed without any warranty.
You should have received a copy of the CC0 Public Domain Dedication along with this software. If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.

keccak.c is based on <https://github.com/gvanas/KeccakCodePackage/blob/master/Standalone/CompactFIPS202/Keccak-more-compact.c>.
ed25519/{ref10,amd64-51-30k,amd64-64-24k} are adopted from SUPERCOP <https://bench.cr.yp.to/supercop.html>.
ed25519/ed25519-donna adopted from <https://github.com/floodyberry/ed25519-donna>.
idea used in main.c' dofastwork() is stolen from <https://github.com/Yawning/horse25519>.