Having both MP_OBJ_NOT_SUPPORTED and MP_OBJ_NULL is arguably confusing.

This is better than forcing each getiter() implementation to raise exception.

travis: Add cross-compilation of mingw port

windows: Enable frozen set and sys.exit

Updated functions now do proper checking that n_kw==0, and are simpler
because they don't have to explicitly raise an exception.  Down side is
that the error messages no longer include the function name, but that's
acceptable.

Saves order 300 text bytes on x64 and ARM.

Likely there are other functions that should be renamed, but this is a
start.

For consistency with MICROPY_MOD_SYS_STDFILES, etc.

mingw: Fix compilation issues

tests: Fix handling of newlines from expected output files on windows

Still not working properly.

This is not fully correct re: error handling, because we should check that
that types are used consistently (only str's or only bytes), but magically
makes lot of functions support bytes.

Two things are handled here: allow to compare native subtypes of tuple,
e.g. namedtuple (TODO: should compare type too, currently compared
duck-typedly by content). Secondly, allow user sunclasses of tuples
(and its subtypes) be compared either. "Magic" I did previously in
objtype.c covers only one argument (lhs is many), so we're in trouble
when lhs is native type - there's no other option besides handling
rhs in special manner. Fortunately, this patch outlines approach with
fast path for native types.

This was hit when trying to make urlparse.py from stdlib run. Took
quite some time to debug.

TODO: Reconsile bound method creation process better, maybe callable is
to generic type to bind at all?

Similar to closure and cell.

Slice value to assign can be only a list so far too.

Includes support for native bases.

Happens regularly when used for debugging.

Need to send a zero-sized packet after sending an exact multiple of 64
bytes (not just after sending 64 bytes exactly).

Addresses issue #494, part 2.

Thumb uses a bit less RAM, bytecode uses a tiny bit more, to avoid
overflow of the dummy buffer in certain cases.

Addresses issue #599.