convert users of the ASSERT and the ASSERT2 macros to standard assert()

opm/core/utility/VelocityInterpolation.cpp

@@ -72,7 +72,7 @@ namespace Opm
             if (cell == grid_.face_cells[2*face]) {
                 face_flux = flux_[face];
             } else {
-                ASSERT(cell == grid_.face_cells[2*face + 1]);
+                assert(cell == grid_.face_cells[2*face + 1]);
                 face_flux = -flux_[face];
             }
             for (int dd = 0; dd < dim; ++dd) {