Calculus Tools 0.8.4

Double Integration!!!! - Be patient with older phones this may take a little bit of time to calculate. It takes anywhere from 1-3 seconds on my Droid @ 1ghz running Froyo so I imagine it could be much longer on other models. It is not as accurate as the single integration because otherwise it might takes minutes. Triple integration would take waaaaaaay too long so I'm probably not going to do it.

I also fixed the bug in the derivative activity with the evaluate showing up not where it was supposed to.