Integrates existing soaring instruments with the soaring sdk

Integrates existing soaring instruments with the soaring sdk

All reviewed aircraft now support total energy compensated variometers and
reuse a common implementation. The following issues have been addressed, either
explicitly or as a benefit from the integration:

 + Fixed incorrect variometer readouts at sim/speed-up values != 1
 + Fixed erratic instrument behavior after pause and reinit
 + Reworked all vario needle animations to be smoother.
 + Fixed ASK13 yaw string. Now it deflects to the correct side.
 + Added temperature and (fake) battery readings to ILEC SC7 digital variometer.
 + Fixed ILEC SC7 sign readout (didn't show the minus sign).

Note: The ASK21 models have not been integrated, as they will need a more
profound cockpit overhaul.