Solves the first diagonal using the GPU
Removed Armadillo due to incompatibility.
Added conversion tool for new matrix format.

* Without Armadillo it's easier to load matrices in the "old" C
  plain format, where the first line of the file presents the
  dimensions of the matrix.
Problems with cudaMemcpy Device To Host
Added after-kernel error checking (no success)
Solved cudaMemcpy issue

* The functions being called for the printf were causing the bug.