Updated teensy to build.

Refactored some stmhal files which are shared with teensy.
Merge branch 'teensy-new' of github.com:dhylands/micropython into dhylands-teensy-new

Conflicts:
	stmhal/pin_named_pins.c
	stmhal/readline.c

Renamed HAL_H to MICROPY_HAL_H.  Made stmhal/mphal.h which intends to
define the generic Micro Python HAL, which in stmhal sits above the ST
HAL.
Merge branch 'dhylands-teensy-new'