Flag to use single layer for entire camera field of view

[softwarefox]

WorldWind currently uses the eye distance to determine the layer to render for a particular map tile. When dealing with multiple layers that have very different imagery data types (such as satellite vs CADRG maps), and the camera angle is tilted, this can result in very different map tiles rendered next to one another.
Suggested enhancement is to allow a flag to be set that specifies that only the lowest-level map layer needed be used to render the entire field of view (even if this results in rendering a map layer outside of its valid altitude range).