Issue with cyipopt

[chiyangW]

The latest document for cyipopt specifies that

The various HSL solvers can be set with linear_solver and the hsllib name must be specified because the default
name ipopt looks for is libhsl.so.

So nlp.add_option('hsllib', 'libcoinhsl.so') must be added after setting the linear_solver. Otherwise it will fail to find the solver even if it's installed.