This improves stack usage in callers to mp_execute_bytecode2, and is step
forward towards unifying execution interface for function and generators
(which is important because generators don't even support full forms
of arguments passing (keywords, etc.)).

This makes sure that only as much stack allocated as actually used, reducing
stack usage for each Python function call.

add methods isspace(), isalpha(), isdigit(), isupper() and islower() to str

For #635 / 25c84643.

Needed to pop the iterator object when breaking out of a for loop.  Need
also to be careful to unwind exception handler before popping iterator.

Addresses issue #635.

msvc: Only update generated headers when there are changes

Based on https://github.com/micropython/micropython/pull/630 by @errordeveloper.

Needs proper coverage testing.  Doesn't implement -ve & -ve.
Addresses issue #611.

This fixes generating the headers casuing complete rebuilds,
even when the headere's content didn't really change.

Also unifies use of SMALL_INT_FITS macro across parser and runtime.

Addresses issue #627.

This reverts commit 6e76f7bc.

This patch tries to workaround a previous clang workaround. Instead of going
into workaround of workaround spiral, the original workaround should be tamed.

windows: Complete rename of MICROPY_PATH_MAX to MICROPY_ALLOC_PATH_MAX (...

Fix unix DEBUG=1 builds

Without this fix, I get the following error:

CC gccollect.c
gccollect.c: In function ‘gc_helper_get_regs’:
gccollect.c:63:1: error: bp cannot be used in asm here

This helps the compiler do its optimisation, makes it clear which
variables are local per opcode and which global, and makes it consistent
when extra variables are needed in an opcode (in addition to old obj1,
obj2 pair, for example).

Could also make unum local, but that's for another time.

Reorder interning logic in mp_obj_new_str, to be more efficient.

str_new is globally accessible, so should be prefixed with mp_obj_.

This removes need for some casts (at least, more than it adds need
for new casts!).

This completes non-automatic interning of strings in the parser, so that
doc strings don't take up RAM.  It complicates the parser and compiler,
and bloats stmhal by about 300 bytes.  It's complicated because now
there are 2 kinds of parse-nodes that can be strings: interned leaves
and non-interned structs.

Merge branch 'keep-strings-uninterned' of github.com:pfalcon/micropython into pfalcon-keep-strings-uninterned

Conflicts:
	py/parse.c