Otherwise, they serve reoccurring source of copy-paste mistakes and
breaking nanbox build.

different HAL versions implement GPIO differently (BSRR vs BSRRH+BSRRL),
this way both drivers are portable between different HAL's

The LCD interface library fails to deassert the chip select of the LCD
after an SPI transmission.  Consequently using the SPI with other
peripherals disturbs the state of the LCD.  This patch changes
lcd.lcd_out() to deassert CS after each transmission to the LCD.

The first argument to the type.make_new method is naturally a uPy type,
and all uses of this argument cast it directly to a pointer to a type
structure.  So it makes sense to just have it a pointer to a type from
the very beginning (and a const pointer at that).  This patch makes
such a change, and removes all unnecessary casting to/from mp_obj_t.

Found these by compiling stmhal with mp_uint_t of type uint32_t instead
of unsigned int.  This actually makes a difference to the code, but just
a curiosity.

Most of the time you don't use the NSS pin of the SPI bus, and so it
shouldn't be enabled by default (this gave some bugs in the past).

Addressing issue #50, still some way to go yet.

Still some method names to iron out, and funtionality to add, but this
will do for the first, basic version.

Blanket wide to all .c and .h files.  Some files originating from ST are
difficult to deal with (license wise) so it was left out of those.

Also merged modpyb.h, modos.h, modstm.h and modtime.h in stmhal/.

Mostly just a global search and replace.  Except rt_is_true which
becomes mp_obj_is_true.

Still would like to tidy up some of the names, but this will do for now.

All board config macros now begin with MICROPY_HW_.

Renamed PYBv10 to PYBV10, since macros should be all uppercase.

Made SDCARD_DETECT configurable in mpconfigport.h, so that the SD
detect pin can be easily configured.

Ultimately all static strings should be qstr.  This entry in the type
structure is only used for printing error messages (to tell the type of
the bad argument), and printing objects that don't supply a .print method.

Can't decide which is better for string type, char or byte pointer.
Changing to char removes a few casts.  Really need to do proper unicode.

This also fixes up the IRQ for the PYBOARD4 USERSW
although I was unable to test that functionality.

* Add missing LCD definitions for STM32F4DISC target, current code
  breaks build.

Can now have null bytes in strings.  Can define ROM qstrs per port using
qstrdefsport.h

A big change.  Micro Python objects are allocated as individual structs
with the first element being a pointer to the type information (which
is itself an object).  This scheme follows CPython.  Much more flexible,
not necessarily slower, uses same heap memory, and can allocate objects
statically.

Also change name prefix, from py_ to mp_ (mp for Micro Python).