Title : mbed-os-mail-5-Bytes-tx-rx

Purpose: Simple application example with 2 threads 
communicating 5-byte buffers through a Mail event-object. 
Target: L432KC / Nboard (from IUT-Cachan)
Tested: YES (2019-01-09)
Author: Jacques-Olivier Klein - IUT de CACHAN
Date: 2018-02-10 rev. 2019-01-09
OS_STACK_SIZE=4096
Libraries: mbed-os rev5345:c966348(03jan2019) + IHMV2 (from IUT-Cachan) rev6:ad91067

2019-01-06 : update mbed-os, IHMV1->V2, Thread::wait(int ms)-> wait(float s), 
ThreadGettid->osThreadGetId, DEFLAULT_STACK_SIZE -> OS_STACK_SIZE,
L432KC Firmare update (ST-LINK) -> test OK. 