objtype: Implement basic framework for subclassing native types.

This implements checking of base types, allocation and basic initialization,
and optimized support for special method lookups. Other features are not yet
supported.
tests: Add basic tests for subclassing native types and using special methods.

Even of these, some features do not yet work as expected.
objtype: Add support for looking up non-method attrs in native base class.
tests: Add test for accessing attribute of inherited native type.
stmhal: Add documentation in comments, and script to generate HTML.

Decided to write own script to pull documentation from comments in C code.
Style for writing auto generated documentation is: start line with ///
and then use standard markdown to write the comment.  Keywords
recognised by the scraper begin with backslash.  See code for examples.

Running: python gendoc.py modpyb.c accel.c adc.c dac.c extint.c i2c.c
led.c pin.c rng.c servo.c spi.c uart.c usrsw.c, will generate a HTML
structure in gendoc-out/.

gendoc.py is crude but functional.  Needed something quick, and this was
it.
stmhal: Oops, typo.
objtype: Support calling normal methods inherited from native base class.

Biggest part of this support is refactoring mp_obj_class_lookup() to return
standard "bound member" pair (mp_obj_t[2]). Actual support of inherited
native methods is 3 lines then. Some inherited features may be not supported
yet (e.g. native class methods, native properties, etc., etc.). There may
be opportunities for further optimization too.
tests: Add test for calling inherited native method on subclass.
nlr.h: As we treat all warnings as errors, can't use #warning.

And this is not good.
py: If setjmp NLR implementation is forced, omit native versions.
py: Abstract no-return attribute for functions a bit.
objfun: Factor out function to report positional args mismatch.
stmhal: Make LED.intensity return the same value it was set to.

Also give proper error message when trying to construct a non-existent
LED.

Addresses issue #530.
stmhal: Reinstate CC3000 driver from old stm/ port.

It's not enabled by default because it doesn't fully work.  It can
connect to an AP, get an IP address and do a host-lookup, but not yet do
send or recv on a socket.
Merge pull request #528 from pfalcon/native-subclass1

Initial support for subclassing native types
stmhal, docs: Small changes to URL links; adds list of files if none given.

This documentation is now available at micropython.org/doc/
Merge branch 'master' of github.com:micropython/micropython
objfun: Add function name accessor and .print slot method.
py: Add tentative scheme for error messages configuration.
py: Add copyright/license header to each file.