For modules I initially created or made substantial contributions to.

How to use this feature is documented in docs/develop/cmodules.rst.

This system makes it a lot easier to include external libraries as static,
native modules in MicroPython.  Simply pass USER_C_MODULES (like
FROZEN_MPY_DIR) as a make parameter.

During make, makemoduledefs.py parses the current builds c files for
MP_REGISTER_MODULE(module_name, obj_module, enabled_define)

These are used to generate a header with the required entries for
"mp_rom_map_elem_t mp_builtin_module_table[]" in py/objmodule.c

As mentioned in #4450, `websocket` was experimental with a single intended
user, `webrepl`. Therefore, we'll make this change without a weak
link `websocket` -> `uwebsocket`.

Configurable via MICROPY_MODULE_GETATTR, disabled by default.  Among other
things __getattr__ for modules can help to build lazy loading / code
unloading at runtime.

The code implements correct behaviour, as tested by basics/module1.py.

Because this function is simple it saves code size to have it inlined.
Being an auxiliary helper function (and only used in the py/ core) the
argument should always be an mp_obj_module_t*, so there's no need for the
assert (and having it would require including assert.h in obj.h).

The API follows guidelines of https://www.python.org/dev/peps/pep-0272/,
but is optimized for code size, with the idea that full PEP 0272
compatibility can be added with a simple Python wrapper mode.

The naming of the module follows (u)hashlib pattern.

At the bare minimum, this module is expected to provide:

* AES128, ECB (i.e. "null") mode, encrypt only

Implementation in this commit is based on axTLS routines, and implements
following:

* AES 128 and 256
* ECB and CBC modes
* encrypt and decrypt

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.

There were several different spellings of MicroPython present in comments,
when there should be only one.

They are one-line functions and having them inline in mp_init/mp_deinit
eliminates the overhead of a function call, and matches how other state
is initialised in mp_init.

    import utimeq, utime
    # Max queue size, the queue allocated statically on creation
    q = utimeq.utimeq(10)
    q.push(utime.ticks_ms(), data1, data2)
    res = [0, 0, 0]
    # Items in res are filled up with results
    q.pop(res)

One can instead lookup __name__ in the modules dict to get the value.

While just a websocket is enough for handling terminal part of WebREPL,
handling file transfer operations requires demultiplexing and acting
upon, which is encapsulated in _webrepl class provided by this module,
which wraps a websocket object.

Currently, only write support is implemented (of limited buffer size).

Seedable and reproducible pseudo-random number generator. Implemented
functions are getrandbits(n) (n <= 32) and seed().

The algorithm used is Yasmarang by Ilya Levin:
http://www.literatecode.com/yasmarang

This leaves behind the common functionality in extmod/machine_mem.c
which can be used by all ports.

Automagically skip related modules.

This for example will allow people to reload modules which didn't load
successfully (e.g. due to syntax error).

This allows the mp_obj_t type to be configured to something other than a
pointer-sized primitive type.

This patch also includes additional changes to allow the code to compile
when sizeof(mp_uint_t) != sizeof(void*), such as using size_t instead of
mp_uint_t, and various casts.

Based on the original patch by Galen Hazelwood:
https://github.com/micropython/micropython/pull/1517 .

Refactored from "stm" module, provides mem8, mem16, mem32 objects with
array subscript syntax.

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.

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.

Given that there's already support for "fixed table" maps, which are
essentially ordered maps, the implementation of OrderedDict just extends
"fixed table" maps by adding an "is ordered" flag and add/remove
operations, and reuses 95% of objdict code, just making methods tolerant
to both dict and OrderedDict.

Some things are missing so far, like CPython-compatible repr and comparison.

OrderedDict is Disabled by default; enabled on unix and stmhal ports.