Cost Increase and 1.3.1 update

This release increases the cost of the AeroRTG by 50%, to offset its aerodynamic nature as compared to the original RTG.

The part continues to function, so this brings it up to date for 1.3.1.

KSP 1.0.5+ update

This version brings the part up to date by:

Moving it to experimentalElectrics
Giving it the same costs and maxTemp as the stock RTG
Adding Core Heat
Correcting typos