Add $(NAME)GetNumInstances() and $(NAME)GetNumBytes() to UAVO template.

This fixes https://github.com/TauLabs/TauLabs/issues/206.

For instance, 

```numWaypointInstances = UAVObjGetNumInstances(WaypointHandle()))```

can be replaced by.

```numWaypointInstances = WaypointGetNumInstances()```

This PR demonstrates the replacement in several functions.

Has not been flight tested.