Additions of wrappers and performance improvement

I've added some wrappers for least squares solvers I regularly use (LSMR and CGLS), these can be downloaded from the standford website. CGLS does not adhere to the usual input argument order CGLS(A,b, ...), therefore I've changed this in my own implementation. If the license on CGLS allows, I could include this version in the spot toolbox?

Using the profiler of matlab, I noticed quiet a large overhead in opSpot.applyMultiply. I've included a fix for that.