Subroutines for real skew-symmetric matrix

[sh-zheng]

Hi, dear developers

We found that in blas/lapack, there were some specific subroutines for real symmetric matrix, but none for real skew-symmetric matrix. A survey in lawn 290 had showed the demand of such kind of subroutines.

So in PR #1049 we realized some basic subroutines including linear solver and eigensolver for skew-symmetric matrix. But the design (naming rule, prototype, data layout, etc) may need some reviews and discusions to check if they are suitable for actual use.