esptool 1.3 now supports both Python 2.7 and 3.4+.
Updated github link to now-official espressif repo.

*a, = b should always make a copy of b, instead, before this patch
if b was a list it would copy only a reference to it.

I.e. they don't run successfully with MICROPY_LONGINT_IMPL_NONE
and MICROPY_LONGINT_IMPL_LONGLONG (the problem is that they generate
different output than CPython, TODO to fix that).

The use of large literal numbers is a big no-no when it comes to writing
programs which work with different int representations. Also, some checks
are pretty adhoc (e.g using struct module to check for 64-bitness). This
change bases entire detection on sys.maxsize and integer operarions, and
thus more correct, even if longer.

Note that this change doesn't mean that any of these tests can pass with
anything but MPZ - even despite checking for various int representations,
the tests aren't written to be portable among them.

INT_MAX used previosly is indeed max value for int, whereas on LP64
platforms, long is used for mp_int_t. Using MP_SMALL_INT_MAX is the
correct way to do it anyway.

nlr_jump is a little bit inefficient because it now saves a register to
the stack.

Each threads needs to have its own private references to its current
locals/globals dicts, otherwise functions running within different
contexts (eg imported from different files) can behave very strangely.

TODO: There's another issue to care about: poll set being modified during
iteration.

Tests which don't work with small ints are suffixed with _intbig.py. Some
of these may still work with long long ints and need to be reclassified
later.

Big aka arbitrary-precision integers (implemented by MPZ module) are used
in tests starting with "int_big_" or ending with "_intbig".

There were 2 bugs, now fixed by this patch:
- after deleting an element the len of the dict did not decrease by 1
- after deleting an element searching through the dict could lead to
  a seg fault due to there being an MP_OBJ_SENTINEL in the ordered array

This fixes unresolved references after [f1ea3bc7]

The renames are:
HAL_Delay -> mp_hal_delay_ms
sys_tick_udelay -> mp_hal_delay_us
sys_tick_get_microseconds -> mp_hal_ticks_us

And mp_hal_ticks_ms is added to provide the full set of timing functions.

Also, a separate HAL_Delay function is added which differs slightly from
mp_hal_delay_ms and is intended for use only by the ST HAL functions.

Render related constants grouped together, with common description.

Also comes with a test for this.  Fixes issue #2904.

User can override PYTHON executable before running script,
gen-cpydiff.py works only with Python3 and most systems register
its executable as 'python3'.