An altitude bar, and orbital speed marked on the drift bar

The orbit takes the lander off the top of the screen, and the panel only
worked while the ground was in sight. Both other bars are rates: they say
how fast, and neither says where.

The altitude bar is height above the surface underneath, up the left edge,
half a pixel of bar to a pixel of sky - the flyable band is about 256
pixels and the screen is 200 tall, so pixel for pixel would run off the
top of the very screen it describes. Above the surface rather than above
some fixed line, so it reads NOUGHT the moment the lander is down.

The marks say where 64 sixteenths is. Without one that number is folklore:
a pilot can feel that somewhere around here the falling stops and has no
way to see where. The bar is a pixel a sixteenth from the middle at 160,
so the marks sit at 224 and at the two pixels before 96, adjacent rather
than overlapping - a bar at orbital speed would otherwise hide the thing
it is being measured against.

Both in magenta. Red and green are taken and they MEAN something here,
how fast and whether it can be landed with, and an altitude is neither.
White was the first choice and the ceiling check counts white to find its
warning, so it read a warning that was never up - the suite caught that.
Cyan was the second and it is the colour of a landing pad, which is
checked as whole cells of it.

groundLevel is factored out of restOnSurface, which had the same sum.

Three checks, each seen to fail on its own break. Two flights, because no
one flight holds both ends of the bar well: the climb reads 219 pixels and
the descent lands and then stays landed. They fly on their own keyboard
file - the shared one holds a key down every forty eight bytes for the
held-thruster check, so borrowing it flew the lander from the keyboard and
the controller at once and turned the gentle descent into a crash.

Tests/expected/cosmosCrossDisk.out

@@ -25,7 +25,7 @@ Mode.sbx                48
 Flip.sbx                173
 Sprite.sbx              442
 Depth.sbx               672
-Lander.sbx              4651
+Lander.sbx              4968
 Pad.sbx                 264
 Crash.sbx               632
 vars.script             50