#include <unistd.h> is only included if not on WIN32 (which does not have unistd.h)
Merge branch 'stable' of github.com:tibnor/acado into tibnor-stable
added symmetric AD functionality, fixed ADbackward, enabled stacking of variables
Merge branch 'master' of github.com:rienq/acado into stable

Conflicts:
	examples/basic_data_structures/function/symbolic_differentiation3.cpp
	external_packages/src/acado_gnuplot/gnuplot_window.cpp
	include/acado/utils/acado_types.hpp
	src/symbolic_operator/projection.cpp
resolved merge conflicts