Renaming NavigatedDisplay's "rotate*" fields.

Hello again!

##### TL;DR:
This isn't applicable to the IDV (unless launched with `-Dpython.security.respectJavaAccessibility=false`), but the changes appear harmless in my testing and it would instantly resolve a problem for a McV user.

##### Gory Details 
Owing to the Python language spec, Jython cannot distinguish between fields and methods that share the same name. `NavigatedDispla`y extending `DisplayMaster` results in Jython essentially overwriting `DisplayMaster.rotate*()` methods with `NavigatedDisplay.rotate*` fields.

The end result is that the `rotate*()` methods can no longer be called via Jython when the `python.security.respectJavaAccessibility` property is set to `false`. This can be verified by running the following Jython from the IDV's Jython Shell (remember to set the property!):

```python
idv.getVMManager().getLastActiveViewManager().getMaster().rotateX(10.)
```

The most straightforward fix appears to be simply renaming the fields.