Moving Arbitrary[_] instances into a central location.
fix Rational#toString bug
fix some hashCode/equals issues
arbitrary updates
fix some CReal bugs
Fix some Quaternion[_] bugs uncovered by CReal.

There is still possibly some more work to be done. At this point
I believe that nroot, pow, and sqrt all are doing the correct
arithmetic operations. It's possible that there's still a bug in
CReal which might prevent some nroot/pow tests from passing.
Fix hashCode/precision bugs in CReal, Complex, and Quaternion.