Test frames remove anchor body

This pull request fixes #220 . Deprecated use of "anchorBody" interfaces were causing compilation errors in the debug build.  Release builds compiled because these errors were contained in assert expression that were only compiled in debug builds. This PR specifically:

1. Removes all outdated usage of getAnchorBody() and isAnchoredToBody() in testFrames
2. Removes all usage of assert, using ASSERT instead throughout testFrames.
3. Fixes a transposition bug in FixedFrames transform calculations.
You can avoid errors like this just by de-mystifying the ambiguous terms with a comment. If the underlying mobilized body is frame B, the parent fixed frame is P, and the new fixed frame is F, then we are trying to find the transform `X_BF` to cache. We have `X_BP=parent.getTransformInMobilizedBody()`, `X_PF=this->getTransform()`. By lining up the superscripts, `X_BF=X_BP*X_PF`. 

I would advocate that we *never* write any compositions of rotations or transforms without a comment saying exactly what's going on and proving that the sense is correct.