Fix bug introduced in 27fda91c8c5adcf5b32b6bfb1763ffd3c16e8eaf

For parallel computations, the relative path is necessary.
Revert "Make error message for prior violation more explicit by adding second argument to info()"

This reverts commit 2815d5fbd490d17121dc3f413bc7041b26fa18df.
Remove mexErrCheck from k_order_pert to make it obey the noprint-option

Currently, all stochastic solvers put the error code to info(1) and use
print_info to output the error. The only exception was k_order_pert,
which immediately created an error. Thus, the use of k_order_pert did
not allow for continuing after encountering errors, because only
print_info obeys the noprint-option. Replacing mexErrCheck by setting
info should deliver the correct behavior.