unix: Use standard return codes for main

py, unix: Add copyright for modules I worked closely on.

Addresses issue #610.

Debugging output for emit_glue now simplified so that the init and
deinit functions are no longer needed.

__debug__ now resolves to True or False.  Its value needs to be set by
mp_set_debug().

TODO: call mp_set_debug in unix/ port.

TODO: optimise away "if False:" statements in compiler.

When disabling these via mpconfigport.mk or on the commandline,
the correspoding build options are not set and the sources are not
built so the modules should not be added to the
MICROPY_EXTRA_BUILTIN_MODULES list since they are undefined.

Infra for counts of other types is there, need last mile to be implemented.

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.

As in the CPython manual: "Unix programs generally use 2 for
command line syntax errors and 1 for all other kind of errors"

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.