I have seen the CC3200 hanging a couple of times, and according to TI
itself the SOC reset is not reliable, which explains my observations.

Initializing too early caused some of the API functions (wifi_*) to fail
when called in main.py

Currently implements only .uname()

In general the changes are:

1. Peripheral (UART, SPI, ADC, I2C, Timer) IDs start from 1, not zero.
2. Make I2C and SPI require the ID even when there's only one bus.
3. Make I2C and SPI accept 'mode' parameter even though only MASTER
   is supported.

Addresses issue #1285.

It's configurable and only enabled for stmhal port.

That layer is nice, but the CC3200 doesn't need it and getting rid of
it saves ~200 bytes, which are more than welcome.

This is needed to avoid half-open connections.

The reason to have our owm ubinascii module is so that later we
can add crc32 support using the hardware engine.

In particular, dates prior to Mar 1, 2000 are screwed up.

The easiest way to see this is to do:

>>> import time
>>> time.localtime(0)
(2000, 1, 1, 0, 0, 0, 5, 1)
>>> time.localtime(1)
(2000, 1, 2, 233, 197, 197, 6, 2)

With this patch, we instead get:
>>> import time
>>> time.localtime(1)
(2000, 1, 1, 0, 0, 1, 5, 1)

Doh - In C % is NOT a modulo operator, it's a remainder operator.

Effect can be easily achieved by ubinsacii.hexlify(hash.digest()).

This drops the size of unicode_isxdigit from 0x1e + 0x02 filler to
0x14 bytes (so net code reduction of 12 bytes) and will make
unicode_is_xdigit perform slightly faster.

This also pulls out hex_digit from py/lexer.c and makes unichar_hex_digit