strtonum clashes with BSD function of same name, and our version is
different so warrants a unique name.  Addresses Issue #305.

parse: Refactor parse node encoding to support full range of small ints.

Based on suggestion by @dpgeorge at
https://github.com/micropython/micropython/pull/313

Specifically, VM's small ints are 31 bit, while parser's only 28. There's already
MP_OBJ_FITS_SMALL_INT(), so, for clarity, rename MP_FIT_SMALL_INT() to
MP_PARSE_FITS_SMALL_INT().

TODO: De-duplicate DECODE_UINT, etc. definitions.

Assuming we have truncating (floor) division, way to do ceiling division
by N is to use formula (x + (N-1)) / N. Specifically, 63 bits, if stored
7 bits per byte, require exactly 9 bytes. 64 bits overflow that and require
10 bytes.

Support varlen encoding for arbitrary int and uint numbers

Add pin mapping code.

http://docs.python.org/3.3/library/functions.html#__import__ :
"When the name variable is of the form package.module, normally, the
top-level package (the name up till the first dot) is returned, not
the module named by name. However, when a non-empty fromlist argument
is given, the module named by name is returned."

This commit also introduces board directories and moves board
specific config into the appropriate board directory.

boards/stm32f4xx-af.csv was extracted from the STM32F4xx datasheet
and hand-tweaked.

make-pins.py takes boards/stm32f4xx-af.csv, boards/stm32f4xx-prefix.c,
and boards/BOARD-NAME/pins.csv as input and generates the file
build/pins_BOARD_NAME.c

The generated pin file for PYBOARD4 looks like this:
https://gist.github.com/dhylands/9063231

The generated pins file includes all of the supported alternate
functions, and includes upsupported alternate functions as comments.

See the commnet block at the top of stm/pin_map.c for details on
how to use the pin mapper.

I also went ahead and modified stm/gpio.c to use the pin mapper.

To follow up pull request #309.

stm: Initialize sys.path with ["0:/", "0:/src", "0:/lib"].

Fix usart_obj_tx_char

This is compatible with what search path was before sys.path refactor,
with addition of module library path ("0:/lib").

Fix build for netduino and stm32f4disc

Update README to current state of affairs.

GPIO functions are crude, and need to be replaced with better ones!

1. Invite x86 (32-bit) users.
2. Update interpreter name.
3. Update dependency install instructions.

Raw REPL mode is activated by CTRL-A, and allows you to more easily
communicate with the pyboard over the serial channel.  In particular,
automated communication using, eg, pyserial on the PC side.

Support passing positional args as keywords to bytecode functions.

For this, record argument names along with each bytecode function. The code
still includes extensive debug logging support so far.

In particular, unix outputs to stderr, to allow to run testsuite against
micropython built with debug output (by redirecting stderr to /dev/null).

Addresses issue #299.