Fixing example compilation optionn for OSX

example/Grid/0_simple/Makefile

example/Grid/1_stencil/Makefile

example/Grid/2_solve_eq/Makefile

example/Grid/3_gray_scott/Makefile

example/Numerics/PSE/0_Derivative_approx_1D/Makefile

example/Numerics/PSE/1_Derivative_approx_1D_mp/Makefile

example/Numerics/PSE/1_Diffusion_1D/Makefile

example/Plot/0_simple_graph/Makefile

example/Plot/2_PSE_convergence/Makefile

example/SE/0_classes/Makefile

example/SE/1_classes/Makefile

example/VCluster/0_simple/Makefile

example/Vector/0_simple/Makefile

example/Vector/1_celllist/Makefile

example/Vector/2_expressions/Makefile

install