appears still to be indicating.
Added a 'caged' property to the AI, for aerobatic work.
Temporarily disabled tumbling due to pitch, until I can learn more
about it.
Publish the current amount of tumble (-1.0:1.0) under
/instrumentation/attitude-indicator/tumble-norm.
a spinning gyro.
Changed FGInstrumentMgr to inherit from FGSubsystemGroup, greatly
simplifying the (already simple) class. I should probably rename this
to FGInstrumentGroup or something similar, but not today.
Added the gyroscopic turn indicator (part of the TC).