Show altitude and vertical speed even when farther away from planet

Currently the altitude is only shown when in the rotating frame of the planet. The rotating frame ends beyond atmosphere or highest mountains (whichever is higher). This PR changes this to show the altitude up to 10000km or 0.5 planet radii (whichever is lower). For more than 100km the altitude is shown in km instead of m.

Furthermore, the vertical speed is shown together with the altitude. Note: This is really the vertical speed, **not** the change in altitude, i.e. it will show zero when you fly horizontal, but the altitude may nevertheless drop if you fly above raising terrain.