Added toDenseVector on DenseMatrix
Additional implicits to DenseMatrix for axpy and zipMapValues
Addition of an MutableInnerProductSpace defined on a DenseMatrix[Double]
Modifying the way norm works for innerproductspaces by default.
assertions for Poisson mean >= 0
don't expose the dense matrix dot product unless 

you really want it.
minor docs
removing a few warnings and cruft
some bug fixes to Scaling.
Make sum only go over activevalues. closes #8