Supports suspend and hibernate modes. Waking is possible throug GPIO
and WLAN.
The mpcallback class is generic and can be reused by other classes.

Also add another method to change the pin's interrupt mode
on the fly.

Such functions are never used after MicroPython has started, and they
remain in RAM wasting space. Now they are placed in a special section
named "boot" which sits just before the heap, allowing us to extend
the effective heap area up to the new boot section. Right now, this
gives us back ~1K, but in the future, more functions might end up in
there as well.

The safe boot pin, when pulled high during reset rolls back the
firmware to the "factory" image and skips execution of 'boot.py'
and 'main.py'. This is useful to recover from a crash condition.
The system led is used mostly to signal errors.

Also improve pybsd, and make it save it's pin configuration.
This is a necessary step towards supporting the CC3200 low
power deep sleep (LPDS) mode.

These definitions help on making modwlan.c usable by other ports
with the CC3100.

Also change other methods' names to make them consistent.

Use the simplelink wrappers instead. This is one step further
towards having a single module for the cc3200 and the cc3100.

This is how it should be, so one knows exactly where the includes are
coming from.

I2C objects can be freed by the GC and a __del__ method is provided
in order to de-init the peripheral prior to being garbage collected.
UART objects are now added to a local list and this list is now part
of the VM_STATE.

Now all ports can use pybstdio.c to provide sys.stdin/stdout/stderr, so
long as they implement mp_hal_stdin_* and mp_hal_stdout_* functions.

This change helps making the cc3200 port API a bit closer to stmhal.
The ramaining differences are due to the specific hardware details
of each chip. One feature that has been deliberately disabled is the
possibility to add custom names and custom pin mappings. Those
features are nice and convenient, but in this port, code size is a
major concern.

The port currently implements support for GPIO, RTC, ExtInt and the WiFi
subsystem. A small file system is available in the serial flash. A
bootloader which makes OTA updates possible, is also part of this initial
implementation.