py: Change nlr_jump to nlr_raise, to aid in debugging.

This does not affect code size or performance when debugging turned off.

To address issue #420.
diff --git a/py/objexcept.c b/py/objexcept.c
index 1165102..51e7a26 100644
--- a/py/objexcept.c
+++ b/py/objexcept.c
@@ -48,7 +48,7 @@
     mp_obj_type_t *type = type_in;
 
     if (n_kw != 0) {
-        nlr_jump(mp_obj_new_exception_msg_varg(&mp_type_TypeError, "%s does not take keyword arguments", mp_obj_get_type_str(type_in)));
+        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError, "%s does not take keyword arguments", mp_obj_get_type_str(type_in)));
     }
 
     mp_obj_exception_t *o = m_new_obj_var(mp_obj_exception_t, mp_obj_t, n_args);