Make failed request for captcha/bot form show a little error text.
Make CHALLENGE_INCLUDES_IP "1" = on, anything else = off instead of needing to be unset.
- memory and time params customisable as well as "difficulty", default 1 iteration, 6000KB, 3 difficulty.
- updated the noscript bash method to work with argon2
- works in webworkers or main thread, capped at 8 threads (doesn't seem to crash firefox anymore -- we could go higher)
- Move to new scheme with some hashing, sigs, and a random user key. close#13
- Change to sha256 rather than sha1 (temporary, but i guess its slightly more secure which is nice for now) ref #10
- Change POW output checked value
- Add lib for randombytes, udpate lua sha lib
- Remove outdated difficulty checks in frontend (was hardcoded 0 anyway) and since algo change is coming soon, there is no need to keep it
