Add keyword argument 'memaddr_use_16b' to i2c.mem_read and mem_write methods
to allow these methods to transmit 16 bit addresses to an i2c device
Add 'memaddr_use_16b' to qstrdefsport.h
Incorporate stylistic changes suggested by @dhylands
Merge https://github.com/micropython/micropython
Initial commit of Myriad2 board-specific configuration files
Merge https://github.com/micropython/micropython
Merge https://github.com/micropython/micropython
Merge https://github.com/blmorris/micropython into Myriad2
Allow DFU_UTIL to be overridden from the environment.
Deal with reading a buffer less than what was allocated.

With this fix, file_long_read now passes.
Change boolean 'use_16bit_addr' to int 'addr_size', can be either 8 or 16 bits, default value is 8
to maintain compatibility with existing code.
remove Myriad2 board config files from master
Merge pull request #767 from dhylands/fix-short-read

Deal with reading a buffer less than what was allocated.
Merge pull request #746 from blmorris/master

Enable 16-bit memory addresses for i2c.mem_read and i2c_mem_write
Merge pull request #766 from dhylands/allow-dfu-override

Allow DFU_UTIL to be overridden from the environment.
stream: Revert to checking for the correct error value.
streams: Treat non-error output size as unsigned.
Add support for storing args during an exception raised by an irq.

The user code should call micropython.alloc_emergency_exception_buf(size)
where size is the size of the buffer used to print the argument
passed to the exception.

With the test code from #732, and a call to
micropython.alloc_emergenncy_exception_buf(100) the following error is
now printed:
```python
>>> import heartbeat_irq
Uncaught exception in Timer(4) interrupt handler
Traceback (most recent call last):
  File "0://heartbeat_irq.py", line 14, in heartbeat_cb
NameError: name 'led' is not defined
```