modsys: Add sys.print_exception(exc, file=sys.stdout) function.
The function is modeled after traceback.print_exception(), but unbloated,
and put into existing module to save overhead on adding another module.
Compliant traceback.print_exception() is intended to be implemented in
micropython-lib in terms of sys.print_exception().
This change required refactoring mp_obj_print_exception() to take pfenv_t
interface arguments.
Addresses #751.
diff --git a/py/obj.h b/py/obj.h
index 3721bea..6db7640 100644
--- a/py/obj.h
+++ b/py/obj.h
@@ -418,7 +418,7 @@
void mp_obj_print_helper(void (*print)(void *env, const char *fmt, ...), void *env, mp_obj_t o_in, mp_print_kind_t kind);
void mp_obj_print(mp_obj_t o, mp_print_kind_t kind);
-void mp_obj_print_exception(mp_obj_t exc);
+void mp_obj_print_exception(void (*print)(void *env, const char *fmt, ...), void *env, mp_obj_t exc);
bool mp_obj_is_true(mp_obj_t arg);