forbid rotating, if at least one of the lasers is too hot

The LB version needs a temperature below 0.1, HQ below 0.25, which is
green temperature level.
account for WR damage in refund, when buying a device

If the player buys the alternative WR to what he's currently got a
possibly damaged device is accounted for. It cuts the refund by half.
increase file version when changing after a release
add general mechanism for storing and loading mission variables

Mission variables should be stored in a local member. A function
has been added to simplify the overhead when loading and storing
mission variables.
formatting
keep storable mission variablen in an array

Rather than syncronizing the code between storing and loading of mission-
variables their names are put into an array and automatically loaded and
assigned or saved.
rename all this.xxx variables to this.$xxx

Variables also have to start with a prefix of either "_" or "$", to avoid
possible name clashes with later versions of Oolite.
change this.$xxx to this._xxx

This is more like other programming languages as the '$' usually is as
special character not usable as variable name.
use dedicated variable instead of boolean flag for heatlevel

This way magic numbers and ternary operators are avoided.
whitespace
reset debugging default values for mission variables to 0
fix comments
add an operation position

This is a virtual position of the WP with the following values:
0: front, 1: storeboard, 2: aft, 3: port
It is set to 0 when bought and rotated accordingly. It will be used
to rotate to a designated position.
rewrite rotation to take a step parameter

So far the rotation was only one step clock- or anticlockwise. Now the
number of steps can be given. Positive integers signify clockwise rotation,
negative integer anticlockwise.

Possible values are +3 +2 +1 -1 -2 -3.
do not delete the rotation time property

Delete just removes the property. As we re-init it just afterwords, we
can just reassign the new value and avoid deletion and recreation of the
property.