Cleanup SQP submodules - only use single evaluation point at a time

[FreyJo]

In some places tmp_ux and ux where used in a mixed way, i.e. compute_fun of constraint modules and what was fixed in #1039

• fixes bug when using globalization and cost computation
• fixes bug in globalization with slacks. Constraint was evaluated with slack values from SQP iterate instead of values from the line search candidate

Implementation:

• Removed all tmp_* pointers in SQP submodules
• Always evaluate at ux
• When one wants to evaluate at another iterate, these pointers have to be temporarily set to another iterate and afterwards reset to the nominal SQP iterate, as done in ocp_nlp_evaluate_merit_fun now.

[giaf]

It looks good!