#15 ETA incorrect in move editor

[Chris Shaffer]

The ETA comments that are inserted in the orders file by
the move editor assume that cargo ships carrying cargo
are fully loaded. Thus, I have a ship with cargo capacity
1.25 loaded with .2 COL showing ETA 3 turns, when the
ETA is actually only 2 turns. The forecaster shows the
correct ETA. This bug does not occur if the cargo ship
has 0 cargo onboard, in which case the correct unloaded
speed is used.

For example:

s 12 192 ; ETA 3 turns

should have been:

s 12 192 ; ETA 2 turns