Merge remote-tracking branch 'upstream/master'

py/builtin.c

py/builtin.h

py/builtinimport.c

py/mpconfig.h

py/obj.c

py/objfun.c

py/objint.c

py/objint.h

py/objstr.c

py/runtime.c

py/runtime.h

stm/audio.c

stm/lcd.c

stm/main.c

stm/printf.c

stm/pybwlan.c

stm/std.h

stm/string0.c

stm/timer.c