Replaced ssym with SX::sym in the symbolic core, #983
Replaced msym with MX::sym in the symbolic core, #983
Re-enable NLP tests for other solver
Unittests for Snopt correction
Adding Snopt find_package to build system
Adding Snopt makefile to build system
Adding Snopt find_package to build system (2)
Removed current ssym, msym, MX(string) usage, #983
Revert "Adding Snopt find_package to build system (2)"

This reverts commit bb8ef151e4676c16459bfac3287312f3c261d698.
Recommitted parts of bb8ef151e4676c16459bfac3287312f3c261d698
Removed flatten, flattenNZ, flattenNZcat, #983
Updated Octave tests, #983
Update limitPrinting_c.cc
Added MX constant constructors, #982
Fixed limitPrinting.hpp
Fixes to examples: SX.sym, flatten
Moved MX::zeros, MX::ones, Matrix::zeros, Matrix::ones to base class, #983
Adding deprecation warnings for ssym, msym
Updated Matrix::sparse, #982
SnopSolver: adding inline documentation