GELQS, GEQRS outdated

[angsch]

Please consider deprecating GELQS and GEQRS.

• There is no easy way to query the workspace to actually use the routines
• The documentation has errors (especially GELQS)
• The triangular system could do with a check of the diagonal for zeros, i.e., be solved with TRTRS, and not TRSM

GELS is a better and safer alternative. GELS wraps the matrix factorization (which GE[LQ,QR] require as input), the right-hand side transform and the solution of the triangular system in a coherent form. It solves a strict superset of what GE[LQ,QR]S can solve.

If you prefer to fix the routines rather than deprecating them, I am happy to create a PR.