This includes file and socket objects, backed by Unix file descriptor.
This improves compatibility with stmhal's uselect (and convenience of
use), though not completely: return value from poll.poll() is still
raw file descriptor.

That apparently will only help folks who read the docs on how to disable,
but could use a quick reminder straight in boot.py. For the developers,
it's important to have debug logging enabled in development branch
(master).

This goes bit against websocket nature (message-based communication),
as it ignores boundaries bertween messages, but may be very practical
to do simple things with websockets.

Name recv() based a "simplistic", as it can't work robustly in every
environment. All this is to let people concentreate on proper, read()-
based one (and to turn recv() based into a "negative showcase",
explaining what are the pitfalls of such approach).

Namely: flags, cachesize, pagesize, minkeypage.

In the sense that while GET_FILE transfers its data, REPL still works.
This is done by requiring client to send 1-byte block before WebREPL
server transfers next block of data.

Requires firmware generated by the latest makeimg.py (which stores size
and md5 of the firmware together with the firmware itself).

md5 is calculated over the entire file, except first 4 bytes, which contain
flash parameters and may be changed by flashing tool or MicroPython flash
auto-config.

This version of the logo may be useful for displaying on small
devices to show that they use MicroPython.

These macros are broken and are anyway unused on these two ports.  If they
are ever needed in the future then their implementation can be taken from
either stmhal (working macros in mpconfigport.h) or esp8266 (functions).

Using __errno() function, and redirect it to use mp_stream_errno from
stream module. This is pre-requisite for integrating with 3rd-party libs,
like BerkeleyDB.

Requires "embedded" BerkeleyDB BTree implementation.

It allows to access files via a virtual method tables and thus can integrate
with MicroPython's stream objects.

Some boards (like the GHI Electronics G30 Dev Board) don't use
NSS at all and rather just use GPIO chip selects.

When compiling with msys2's gcc there's no need to apply the binary fmode
so adjust the Makefile to reflect that.
When compiling with mingw we need to include malloc.h since there is no
alloca.h, and the 64bit detection in mpconfigport.h needs some adjustment.

To filter out even prototypes of mp_stream_posix_*() functions, which
require POSIX types like ssize_t & off_t, which may be not available in
some ports.