Support CUDA and use MAGMA as backend

[Zhen Zhong]

http://icl.cs.utk.edu/magma/index.html MAGMA is a solid implementation of BLAS and linear algebra routines for multicore and GPU systems.

[Klaus Iglberger]

Hi Dysis!

Thanks a lot for the proposal. We will look into this, but since GPUs have a low priority for us we will focus on more urgent issues first. Thanks again,

Best regards,

Klaus!

[Klaus Iglberger]

Issue #182 was marked as a duplicate of this issue.