Merge remote-tracking branch 'upstream/master'

py/builtin.c

py/builtinmath.c

py/objcomplex.c

py/objfloat.c

py/objstr.c

py/parsenum.c

py/parsenum.h

py/runtime.c

py/showbc.c

stm/math.c

stmhal/Makefile

stmhal/accel.c

stmhal/accel.h

stmhal/import.c

stmhal/led.c

stmhal/led.h

stmhal/main.c

stmhal/math.c

stmhal/pybmodule.c

stmhal/usb.c