py: Add LOAD_SUPER_METHOD bytecode to allow heap-free super meth calls.
This patch allows the following code to run without allocating on the heap: super().foo(...) Before this patch such a call would allocate a super object on the heap and then load the foo method and call it right away. The super object is only needed to perform the lookup of the method and not needed after that. This patch makes an optimisation to allocate the super object on the C stack and discard it right after use. Changes in code size due to this patch are: bare-arm: +128 minimal: +232 unix x64: +416 unix nanbox: +364 stmhal: +184 esp8266: +340 cc3200: +128