Fix camera Eye and Target Elevations to be offset from *original* level

[bill_gilliss]

When  you create a camera view, you set its initial height as an offset from the current level:

When editing the camera height, however, its height is shown as an offset not from the current level, but from Level 1:

This makes it very hard to set the height above the current level with any accuracy without going back to a view that shows the levels and doing the math to determine the desired camera height. I'd like to see the Eye And Target elevations here as Level: and Offset:, just as when the camera was created.