Usage:

    import machine
    wdt = machine.WDT(0, 5000) # 5 second timeout
    wdt.feed()

Thanks to Moritz for the initial implementation.

There was a bug in `framebuf1_fill` function, that makes it leave a few
lines unfilled at the bottom if the height is not divisible by 8.

A similar bug is fixed in the scroll method.

This makes it more efficient at runtime to hash str/bytes objects.

Makes it easier to access them without passing around another dict of the
config values.

Arguments of an unknown type cannot be skipped and continuing to parse a
format string after encountering an unknown format specifier leads to
undefined behaviour.  This patch helps to find use of unsupported formats.

With backwards compatibility for pyboard.

The idea is that all ports can use these helper methods and only need to
provide initialisation of the SPI bus, as well as a single transfer
function.  The coding pattern follows the stream protocol and helper
methods.

This extra forward slash for the starting-point directory is unnecessary
and leads to additional slashes on Max OS X which mean that the frozen
files cannot be imported.

Fixes #2374.

Or alternatively, refer to an exact library file, not just phony target
"lib".

And remove reference to deprecated pyb.delay() and pyb.millis().

This allows 1-wire drivers (eg DS18X20) to perform in-place operations and
hence do less memory allocations.

The OneWire class is now in its own onewire.py module, and the temperature
sensor class is in its own ds18x20.py module.  The latter is renamed to
DS18X20 to reflect the fact that it will support both the "S" and "B"
variants of the device.

These files are moved to the modules/ subdirectory to take advantage of
frozen bytecode.

Use the `SPI` factory function in the examples, and use
proper baud rate of 80 000 000.

It has reliability issues (cause unknown at this time).

This rename was missed in the previous patch.

Also at _t to mp_exc_stack pre-declaration in struct typedef.

Try to un-mount a file system and re-mount it again.