Rewisp 0.20.1 — faster recall

Asking Rewisp something is about four times faster.

Searching your memory by meaning was reloading every wisp's fingerprint from disk each time you asked a question, then doing it again for each part of that question. Rewisp now keeps them ready and adds new ones as they arrive.

On a 12,000 wisp memory that took a typical question from around 96ms of searching down to 26ms. It stays fast as your memory grows.

Forgetting still works exactly as before — anything you delete leaves the search immediately, and restoring a backup is handled properly too.

Also fixed: a single corrupted wisp could previously break meaning-based search entirely. Now it is skipped and everything else keeps working.