Added the updated interface to HPMPC
Making Hessian symmetric changed from warning to info.
If testing is ON, warnings are considered as a failure.
Merge branch 'master' of github.com:mvukov/acado into issue_111
Revert "Making Hessian symmetric changed from warning to info."

This reverts commit a6054deb8a07366f704612c0502e280b85addbde.
Fixing a6054de.
Merge branch 'master' of github.com:mvukov/acado into issue_111
Fixing the symbolics API, issue #111
Fixing the fourtankNMPC.cpp example
Fixing parameter_estimation_tutorial2.cpp example
Trying to fix the powerkite_on.cpp example
powerkite_on.cpp example fails, move it to dev