Heat Pump fixes

Both heatDissipation / heatConductivity can be configured from part cfg file.
heatDissipation / heatConductivity given stock default of 0.12f
heatDissipation / heatConductivity will affect corresponding Part properties.
heat pumps no longer gain heat from cooled target by default. (can be added back in via heatGain)
heatTransfer default changed from 0.0f to 1.0f

Net changes as configured: Heat Pumps no longer interfere in their own cooling process. Can actually cool H2 tanks below their boiling points.