Add artificial misspelling

[huertanix]

Users will occasionally misspell their search terms, so there should be a function that will take in a string and swap out a random selection of characters within a "reasonable" range of randomness. The function should have a higher chance of swapping characters for other characters physically near them on a US keyboard, which should cover most spelling errors, with a small chance of truly random character swapping to cover the possibility of a user spelling error that falls outside the close-key algorithm.

I have no idea what to do if people are incredibly horrible spellers and add more letters or get it totally wrong. They get a free ride in the FBI party van I guess.