Addresses issue #1117.

Addresses issue #1119.

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.

Apparently the order of interface numbers should be sequential and
increasing in a config descriptor.  So as to retain compatibility with
Windows drivers for the CDC+MSC and CDC+HID modes, we move the CDC
configs to the end of the descriptors, instead of changing the interface
numbers.

See PR #957 for background.

Different HID modes can be configured in Python.  You can either use
predefined mouse or keyboard, or write your own report descriptor.

The unused files are from the ST demos for different USB classes and are
not needed for the stmhal port.

Addresses issue #1113.

Also gives line number of location of error.  Very useful!

These are useful for implementing atomic lock operations.

Saves 8 bytes C-stack on stmhal and 16 bytes on unix x86.

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.

Addresses issue #1109.