Terrain profile doesn't display on 2D globe

[wcmatthysen]

Migrated issue from: NASAWorldWind#55.

The TerrainProfile example exposes a flat globe option, which when selected, causes the terrain profile window to disappear.

I just ran the TerrainProfiler example and it still seems to be an issue in the latest build.

3D Globe:

Flat Globe:

[nebsar]

Because in Flat Globe elevations are not loaded.