Lastworking

See merge request !12

# Conflicts:
#   include/display.h
#   include/interrupt-io.h
#   include/sensors.h
#   include/switches.h
#   include/train-controller.h
#   include/types.h
#   lib/Makefile
#   lib/display.c
#   lib/interrupt-io.c
#   lib/io-api.c
#   lib/k4.c
#   lib/sensors.c
#   lib/switches.c
#   lib/train-controller.c
#   src/Makefile

update: 1.await accepts negative event id, it allows us put 2 notifiers for uart1 at the same slot ,one in awaittask another in data. 2. for uart1, we enable and disable it by writing to control register in uart1 rather than in irq. 3. todo: clearing interrupt in uart1