Addresses issue #1022.

Add a command for converting the WAV files to the amp skin tutorial, so that people can use their own files easily.

We are not word-for-word compatible with CPython exceptions, so we are
free to make them short but informative in order to reduce code size.
Also, try to make messages the same as existing ones where possible.

Reduces code size when MICROPY_ERROR_REPORTING_TERSE is selected.

- remove single string initialization style
- take list of strings instead
- store list in the type for fast lookup

Addresses issue #1027.

To make mp_obj_new_int_from_float() somehow work.

This fixes conversion when float type has more mantissa bits than small int,
and float value has small exponent. This is for example the case of 32-bit
platform using doubles, and converting value of time.time(). Conversion of
floats with larg exponnet is still not handled correctly.

We don't have an explicit ChangeLog file, but don't really need one
because we use a good version control system.  This script is useful if
you need a pretty-printed ChangeLog for some reason.

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.