py: Add NLR support for xtensa CPU.
esp8266: New port of Micro Python to ESP8266 wifi module.
esp8266: Allow to override serial port.
esp8266: Provide sensible default ESP_SDK; deploy 2 the images together.
esp8266: Change bignum from mpz to longlong; move some rodata to iram.

Some rodata items can go in iram/irom segment, but not others.  With
this patch ESP now has 24256 bytes of heap ram.  It passes 228 out of
248 tests from tests/basics directory.
Update uheapq.rst

Erratum in froh.
docs: Bump version to 1.3.7.
esp8266: Make default ESP_SDK variable work correctly.

When esp-open-sdk is built with STANDALONE=y (the default) then ESP_SDK
is set to the correct value, so that "make" just works.
modubinascii: Add, with hexlify() implementation.
esp8266: Move more rodata to irom section.

rodata can only go in iram/irom if it's accessed only using word loads
(ie no byte or half-word access).
Use MP_DEFINE_CONST_DICT macro to define module dicts.

This is just a clean-up of the code.  Generated code is exactly the
same.
tests: Split out float test from builtin_round.py.
esp8266: Add README.md.
stmhal: Add USB_VCP.setinterrupt method, to disable CTRL-C.