This is for efficiency, so we don't need to subtract 1 from the ip
before storing it to code_state->ip.  It saves a lot of ROM bytes on
unix and stmhal.

Should have done it before tagging...

This allows to pring either absolute addresses or relative offsets in jumps
and code references.

Mirroring ip to a volatile memory variable for each opcode is an expensive
operation. For quite a lot of often executed opcodes like stack manipulation
or jumps, exceptions cannot actually happen. So, record ip only for opcode
where that's possible.

Patches to fatfs for our use will follow.

This patch makes the MICROPY_PY_BUILTINS_SLICE compile-time option
fully disable the builtin slice operation (when set to 0).  This
includes removing the slice sytanx from the grammar.  Now, enabling
slice costs 4228 bytes on unix x64, and 1816 bytes on stmhal.

This patch makes MICROPY_PY_BUILTINS_SET compile-time option fully
disable the builtin set object (when set to 0).  This includes removing
set constructor/comprehension from the grammar, the compiler and the
emitters.  Now, enabling set costs 8168 bytes on unix x64, and 3576
bytes on stmhal.

This script is rewrite of run-tests-exp.sh, and tries to achieve self-hosted
testsuite running in environments where neither CPython nor unix shell is
available. As run-tests-exp.sh, it requires complete set of .exp files
pre-generated with ./run-test --write-exp.

It seems the Mac will happily wipe out at least some of the data on
a freshly reset filesytem, if the filesystem was reset while plugged
into the Mac.

system() is the basic function to support automation of tasks, so have it
available builtin, for example, for bootstrapping rest of micropython
environment.

This renders it in yellow/orange box on RTD server.

This optimisation reduces the VM exception stack element (mp_exc_stack_t)
by 1 word, by using bit 1 of a pointer to store whether the opcode was a
FINALLY or WITH opcode.  This optimisation was pending, waiting for
maturity of the exception handling code, which has now proven itself.

Saves 1 machine word RAM for each exception (4->3 words per exception).
Increases stmhal code by 4 bytes, and decreases unix x64 code by 32
bytes.

This patch gives proper SyntaxError exceptions for bad global/nonlocal
declarations.  It also reduces code size: 304 bytes on unix x64, 132
bytes on stmhal.

Helps other ports.

This saves around 100 bytes code space on stmhal, more on unix.

This speeds up writes significantly.

Just adjust line-endings of micropython.exe output, the rest should be
handled by Wine (automagically on properly configured distro).

To run:

MICROPY_MICROPYTHON=../windows/micropython.exe ./run-tests