Get speed and heading from NMEA RMC sentences

fixes: #48
4 jobs for speed_from_nmea_rmc in 1 minute and 49 seconds (queued for 1 second)
latest
Status Job ID Name Coverage
  Test
passed #268945
ubuntu-16.04

00:01:38

passed #268946
ubuntu-17.10

00:01:49

passed #268947
ubuntu-18.04

00:01:39

passed #268948
ubuntu-18.04-no-backend

00:01:38