Adjusted sobol cache usage to make an entry for every string/search combination or...

Adjusted sobol cache usage to make an entry for every string/search combination or not use the cache at all. This is a more correct way of handling things, and anyone worried about too many cache entries from sobol can just increase the size of their cache. Also, sobol now caches search instances rather than just results - searches like GoogleSearch can now persist non-result state acquired with the results.