This method follows the new HW API and allows to set a hard or soft IRQ
callback when a Pin has a level change. It still remains to make this
method return a IRQ object.
Make a clearer distinction between init functions that must be done
before any scripts can run (xxx_init0) and those that can be safely
deferred (xxx_init).
Fix bug initialising USB VCP exception. Addresses issue #788.
Re-order some init function to improve reliability of
reset/soft-reset.
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/.
This is an attempt to clean up the Micro Python API on the pyboard.
Gpio functionality is now in the Pin object, which seems more natural.
Constants for MODE and PULL are now in pyb.Pin. Names of some
classes have been adjusted to conform to CamelCase. Other
miscellaneous changes and clean up here and there.