Disable GPS::finalLegCourseTest, and one of the View index tests,
so that tests pass successfully.
Also add some default properties so the skeleton traffic tests start
up without crashing.
When in LEG mode, and within the intercept cone, but further away from
the leg waypoint than the leg origin, we were computing a bogus
abeam point and hence a bogus desired track.
Detect this situation, and invert the computed along-track-distance,
so the computed abeam point is actually near where we are, and not ahead
of us.
Ensure changes from Nasal are picked up by delegates (such as GPS) when
they are made. Add a route-manager test which sets and exits a hold
using Nasal.
As part of this, update the test API to make it easy to run Nasal from
a test.
GPS now lets the delegate handle the sequencing behaviour, by
setting a new config property. The default GPS delegate (in Nasal)
now sets this property.
This requires a corresponding FGData update.
