So now all printing should go via either mp_plat_print or
mp_sys_stdout_print.

Previous to this patch the printing mechanism was a bit of a tangled
mess.  This patch attempts to consolidate printing into one interface.

All (non-debug) printing now uses the mp_print* family of functions,
mainly mp_printf.  All these functions take an mp_print_t structure as
their first argument, and this structure defines the printing backend
through the "print_strn" function of said structure.

Printing from the uPy core can reach the platform-defined print code via
two paths: either through mp_sys_stdout_obj (defined pert port) in
conjunction with mp_stream_write; or through the mp_plat_print structure
which uses the MP_PLAT_PRINT_STRN macro to define how string are printed
on the platform.  The former is only used when MICROPY_PY_IO is defined.

With this new scheme printing is generally more efficient (less layers
to go through, less arguments to pass), and, given an mp_print_t*
structure, one can call mp_print_str for efficiency instead of
mp_printf("%s", ...).  Code size is also reduced by around 200 bytes on
Thumb2 archs.

When setting usb_mode to "HID", hid config object now has
polling-interval (in ms) as the 4th element.  It mmust now be a 5-tuple
of the form:

(subclass, protocol, max_packet_len, polling_interval, report_desc)

The mouse and keyboard defaults have polling interval at 8ms.

Because it's only a compiler optimization and increases code size.

This new method allows to assign an static IP to the device.

In particular, numbers which are less than 1.0 but which
round up to 1.0.

This also makes those numbers which round up to 1.0 to
print with e+00 rather than e-00 for those formats which
print exponents.

Addresses issue #1178.

This simplifies the API for objects and reduces code size (by around 400
bytes on Thumb2, and around 2k on x86).  Performance impact was measured
with Pystone score, but change was barely noticeable.

Saves 768 bytes code space on Thumb2 archs.

This has implications all over the place. I have to admit that
you can instantly see that usability improves, but it costs 3K.
At the same time I took the oportunity to rename the '/SFLASH'
drive to '/flash' which improves compatibility with the pyboard.

Fixes msvc linker warnings about mismatching sizes between the mp_obj_fdfile_t
struct defined in file.c and the mp_uint_t declarations found in modsys.c and modbuiltins.c

Also prevents some of the weaker syntax parsers out there treating the whole
'*/*const*/' part as a comment

This patch gets full function argument passing working with native
emitter.  Includes named args, keyword args, default args, var args
and var keyword args.  Fully Python compliant.

It reuses the bytecode mp_setup_code_state function to do all the hard
work.  This function is slightly adjusted to accommodate native calls,
and the native emitter is forced a bit to emit similar prelude and
code-info as bytecode.