This also adds these applications to the CI tests. The following drivers
have been modelled:
gp2y10xx
grove_ledbar
hd44780
hdc1000
hih6130
hmc5883l
hts221
ili9341
ina2xx
ina3221
io1_xplained
isl29020
isl29125
itg320x
jc42
my9221
Replace direct accesses to sched_active_thread and sched_active_pid with
the helper functions thread_getpid() and thread_get_active(). This serves
two purposes:
1. It makes accidental writes to those variable from outside core less likely.
2. Casting off the volatile qualifier is now well contained to those two
functions
