Reimplemented improved searches on /explore and /earn

Implemented a new improved search on /earn and /explore.  

/earn should now be much faster than it is now.  When not searching (no criteria entered in the boxes), it takes about half as long as the current version.  When searching, it can be an order of magnitude faster than the current version.  This is a pretty significant improvement from the previous version I checked in, which, rather than speeding things up, made everything suck.

My original attempt at /explore was actually fine, so that is reimplemented as-is.  That page as-is is very slow, though, and could use the same improvements to performance that I made to /earn with this change, but I will hold off on that.