When the rover goes into guided mode it sets the current location as
the guided point to goto. If the rover is stationary when this
happens no problem. If however the rover is still rolling (say going
from AUTO to GUIDED) then the rover would go past its guided position
and get confused and begin to circle it. This change resolves that issue.
As the previous commit as doubled the number of reads required to
confirm that the mode change switch has been changed this means it
will halve the speed it changes at. So we double the rate at which we
read it to keep things consistent.