Addresses Issue #199.

Also fixes a bug in the for-in-range optimiser.

I hope to remove break and continue byte codes in the future and just
use jump (if possible).

Fix malformed makeqstrdata generated file when using python 2.7

f2d and d2f functions from libgcc does not work correctly, most likely
due to the ABI being incorrect.  libgcc disabled for now.

mpconfigport.h is now included by stm32f4xx.h so that all STM files have
access to these defines.

Remove hardcoded PLL_M value

Conflicts:
	py/objstr.c
	py/py.mk
	py/stream.c
	unix/main.c
	unix/socket.c

Can now have null bytes in strings.  Can define ROM qstrs per port using
qstrdefsport.h

* Add the option to pass OSC frequency on command line.

Note that splitting by explicit string is not implemented so far.

Also, support negative indexes.

Currently, MicroPython strings are mix between CPython byte and unicode
strings. So, conversion is null so far. This dummy implementation is
intended for compatibility with CPython (so, same code can run on both).

CPython _socket actually have only those and doesn't provide stream
interface (higher-level CPython "socket" what adds this).

+516 bytes x86.

A file cannot be iterated concurrently, so we make io.FileIO its own
iterator.

Uses stream_unbuffered_readline underline.

Useful as getiter method for objects which are their own iterators, etc.

Expose memory stats functions via "micropython" module.

These are micropython.mem_total(), .mem_current(), .mem_peak(). These are 3
individual functions with simple scalar return value to make sure that
calls to these functions themselves have minimal (hopefully zero) impact on
memory allocation.