Add these methods to this "GPIO output emulated with console prints"
config.

While this console API improves handling on real hardware boards
(e.g. clipboard paste is much more reliable, as well as programmatic
communication), it vice-versa poses problems under QEMU, apparently
because it doesn't emulate UART interrupt handling faithfully. That
leads to inability to run the testsuite on QEMU at all. To work that
around, we have to suuport both old and new console routines, and use
the old ones under QEMU.

We want to close communication object even if there were exceptions
somewhere in the code. This is important for --device exec:/execpty:
which may otherwise leave processing running in the background.

Ideally, these should be configurable from Python (using network module),
but as that doesn't exist, we better off using Zephyr's native bootstrap
configuration facility.

The poweroff() and poweron() methods are used to do soft power control of
the display, and this patch makes these methods work the same for both I2C
and SPI interfaces.

After a poweroff(), the poweron() method does a soft power-on and any
previous state of the display persists.

As it may contain newlines, etc.

When wiznet5k_socket_accept is called, if a socket is established, get the
IP address of the socket.

The binary and unary ops have changed bytecode encoding.

2 non-bytecode binary ops (NOT_IN and IN_NOT) are moved out of the
bytecode group, so this change will change the bytecode format.

Printing "(null)" when a NULL string pointer is passed to %s is a debugging
feature and not a feature that's relied upon by the code.  So it only needs
to be compiled in when debugging (such as assert) is enabled, and saves
roughy 30 bytes of code when disabled.

This patch also fixes this NULL check to not do the check if the precision
is specified as zero.

Because a lot of string processing functions assume there is a null
terminating byte, so they can work in an efficient way.

Fixes issue #3334.

Header files that are considered internal to the py core and should not
normally be included directly are:
    py/nlr.h - internal nlr configuration and declarations
    py/bc0.h - contains bytecode macro definitions
    py/runtime0.h - contains basic runtime enums

Instead, the top-level header files to include are one of:
    py/obj.h - includes runtime0.h and defines everything to use the
        mp_obj_t type
    py/runtime.h - includes mpstate.h and hence nlr.h, obj.h, runtime0.h,
        and defines everything to use the general runtime support functions

Additional, specific headers (eg py/objlist.h) can be included if needed.

Qstr values fit in 16-bits (and this fact is used elsewhere in the code) so
no need to use more than that for the large lookup tables.  The compiler
will anyway give a warning if the qstr values don't fit in 16 bits.  Saves
around 80 bytes of code space for Thumb2 archs.

Building mpy-cross: this patch adds .exe to the PROG name when building
executables for host (eg mpy-cross) on Windows.  make clean now removes
mpy-cross.exe under Windows.

Building MicroPython: this patch sets MPY_CROSS to mpy-cross.exe or
mpy-cross so they can coexist and use cygwin or WSL without rebuilding
mpy-cross.  The dependency in the mpy rule now uses mpy-cross.exe for
Windows and mpy-cross for Linux.

Sending byte-by-byte is inefficient and leads to errors in the WebSocket
protocol when sending utf-8 encoded characters.

CPython docs explicitly state that the RHS of a set/frozenset binary op
must be a set to prevent user errors.  It also preserves commutativity of
the ops, eg: "abc" & set() is a TypeError, and so should be set() & "abc".

This change actually decreases unix (x64) code by 160 bytes; it increases
stm32 by 4 bytes and esp8266 by 28 bytes (but previous patch already
introduced a much large saving).

A lot of set's methods (the mutable ones) are not allowed to operate on a
frozenset, and giving frozenset a separate locals dict with only the
methods that it supports allows to simplify the logic that verifies if
args are a set or a frozenset.  Even though the new frozenset locals dict
is relatively large (88 bytes on 32-bit archs) there is a much bigger
saving coming from the removal of a const string for an error message,
along with the removal of some checks for set or frozenset type.

Changes in code size due to this patch are (for ports that changed at all):

   unix x64:   -56
unix nanbox:  -304
      stm32:   -64
    esp8266:  -124
     cc3200:   -40

Apart from the reduced code, frozenset now has better tab-completion
because it only lists the valid methods.  And the error message for
accessing an invalid method is now more detailed (it includes the
method name that wasn't found).

These now should be caught properly and lead to RuntimeError instead of
crash.

TLS SNI support, fixes after making str.rstrip() behavior compliant.

This returns a complex number, following CPython behaviour.  For ports that
don't have complex numbers enabled this will raise a ValueError which gives
a fail-safe for scripts that were written assuming complex numbers exist.

This adds a new configuration option to print runtime warnings and errors to
stderr. On Unix, CPython prints warnings and unhandled exceptions to stderr,
so the unix port here is configured to use this option.

The unix port already printed unhandled exceptions on the main thread to
stderr. This patch fixes unhandled exceptions on other threads and warnings
(issue #2838) not printing on stderr.

Additionally, a couple tests needed to be fixed to handle this new behavior.
This is done by also capturing stderr when running tests.

Not all can, so we don't need to reserve bytecodes for them, and can
use free slots for something else later.

A unix target should provide POSIX open/write/close functions regardless of
its machine architecture.  Fixes issue #3325.

It removes the need for a wrapper Python function to dispatch to the
framebuf method which makes each function call a bit faster, roughly 2.5x.
This patch also adds the rest of the framebuf methods to the SSD class.

The timer prescaler is buffered by default, and this patch enables ARPE
which buffers the auto-reload register.  With both of these registers
buffered it's now possible to smoothly change the timer's frequency and
have a smoothly varying PWM output.

Allow literal minus in char classes to be in trailing position, e.g. [a-c-].
(Previously, minus was allowed only at the start.)

This increases ARM Thumb2 code size by 8 bytes.