ML API refactoring

Signed-off-by: Christoph M. Wintersteiger <cwinter@microsoft.com>
ML example doc fix

Signed-off-by: Christoph M. Wintersteiger <cwinter@microsoft.com>
ML API refactoring (z3native.c -> z3native_stubs.c)

Signed-off-by: Christoph M. Wintersteiger <cwinter@microsoft.com>
ML API refactoring (z3native.c -> z3native_stubs.c)

Signed-off-by: Christoph M. Wintersteiger <cwinter@microsoft.com>