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.

An issue was due to incorrectly taking size of default strip characters
set.

This patch adds a function utf8_check() to check for a valid UTF-8 encoded
string, and calls it when constructing a str from raw bytes.  The feature
is selectable at compile time via MICROPY_PY_BUILTINS_STR_UNICODE_CHECK and
is enabled if unicode is enabled.  It costs about 110 bytes on Thumb-2, 150
bytes on Xtensa and 170 bytes on x86-64.

The unary-op/binary-op enums are already defined, and there are no
arithmetic tricks used with these types, so it makes sense to use the
correct enum type for arguments that take these values.  It also reduces
code size quite a bit for nan-boxing builds.

Otherwise, it will silently get incorrect result on other values types,
including CPython tuple form like "foo.png".endswith(("png", "jpg"))
(which MicroPython doesn't support for unbloatedness).

  - Changed: ValueError, TypeError, NotImplementedError
  - OSError invocations unchanged, because the corresponding utility
    function takes ints, not strings like the long form invocation.
  - OverflowError, IndexError and RuntimeError etc. not changed for now
    until we decide whether to add new utility functions.

The main case to catch is invalid types for the containment operator, of
the form str.__contains__(non-str).

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

This matches the coding/layout style of all the other objects.

Negative values mean no limit on the number of splits so should delegate to
the .split() method.

Split this setting from MICROPY_CPYTHON_COMPAT. The idea is to be able to
keep MICROPY_CPYTHON_COMPAT disabled, but still pass more of regression
testsuite. In particular, this fixes last failing test in basics/ for
Zephyr port.

This patch changes mp_uint_t to size_t for the len argument of the
following public facing C functions:

mp_obj_tuple_get
mp_obj_list_get
mp_obj_get_array

These functions take a pointer to the len argument (to be filled in by the
function) and callers of these functions should update their code so the
type of len is changed to size_t.  For ports that don't use nan-boxing
there should be no change in generate code because the size of the type
remains the same (word sized), and in a lot of cases there won't even be a
compiler warning if the type remains as mp_uint_t.

The reason for this change is to standardise on the use of size_t for
variables that count memory (or memory related) sizes/lengths.  It helps
builds that use nan-boxing.

These values are used to compute memory addresses and so size_t is the
more appropriate type to use.

Instead of always reporting some object cannot be implicitly be converted
to a 'str', even when it is a 'bytes' object, adjust the logic so that
when trying to convert str to bytes it is shown like that.
This will still report bad implicit conversion from e.g. 'int to bytes'
as 'int to str' but it will not result in the confusing
'can't convert 'str' object to str implicitly' anymore for calls like
b'somestring'.count('a').

The RHS can only be returned if it is the same type as the LHS.

Allows to iterate over the following without allocating on the heap:
- tuple
- list
- string, bytes
- bytearray, array
- dict (not dict.keys, dict.values, dict.items)
- set, frozenset

Allows to call the following without heap memory:
- all, any, min, max, sum

TODO: still need to allocate stack memory in bytecode for iter_buf.

This patch fixes two main things:
- dicts can be printed directly using '%s' % dict
- %-formatting should not crash when passed a non-dict to, eg, '%(foo)s'

In this, don't allocate copy, just return non-empty string. This helps
with a standard pattern of buffering data in case of short reads:

    buf = b""
    while ...:
        s = f.read(...)
        buf += s
        ...

For a typical case when single read returns all data needed, there won't
be extra allocation. This optimization helps uasyncio.

This patch does further refactoring using the new mp_raise_TypeError
and mp_raise_ValueError functions.

Checks for number of args removes where guaranteed by function descriptor,
self checking is replaced with mp_check_self(). In few cases, exception
is raised instead of assert.

Introduce mp_raise_msg(), mp_raise_ValueError(), mp_raise_TypeError()
instead of previous pattern nlr_raise(mp_obj_new_exception_msg(...)).
Save few bytes on each call, which are many.

Default is disabled, enabled for unix port. Saves 600 bytes on x86.

Disabled by default, enabled in unix port. Need for this method easily
pops up when working with text UI/reporting, and coding workalike
manually again and again counter-productive.

It now supports \n, \r and \r\n as newline separators.

Adds 56 bytes to stmhal and 80 bytes to unix x86-64.

Fixes issue #1689.

This reverts commit 6de8dbb4. The change
was incorrect (correct change would require comparing with end pointer in
each if statement in the block).

By comparing with string end pointer instead of checking for NUL byte.
Should alleviate reallocations and fragmentation a tiny bit.

The type is an unsigned 8-bit value, since bytes objects are exactly
that.  And it's also sensible for unicode strings to return unsigned
values when accessed in a byte-wise manner (CPython does not allow this).