Matrix operations missing overloads that accept pre-allocated storage for result

[mjmckp]

There are a few matrix operations that are missing overloads that accept pre-allocated storage for the result. In particular, the Matrix instance methods Transpose, Cholesky, QR, and Evd suffer from this (there may be others, but these three are the ones of interest to me). The overloaded signature for Transpose is straightforward, but that for Cholesky, QR, and Evd could either take a pre-existing Cholesky, QR, or Evd objects, or matrices to use for the underlying Cholesky Factor or Q and R or D and Eigenvalues matrices.