Update aerocalc.js

Planet properties for Eve, Duna, and Jool updated according to their wikis. Also modified planet constructor comments specifying units.

http://wiki.kerbalspaceprogram.com/wiki/Eve
http://wiki.kerbalspaceprogram.com/wiki/Duna
http://wiki.kerbalspaceprogram.com/wiki/Jool
Merge pull request #3 from shinji144/patch-1

Update aerocalc.js