Incomplete fix of editor mass discrepancies

The editor shows incorrect mass information for tanks in the new "i" toolbar button, like what is shown here: https://imgur.com/ahra20t.  This tries to fix the masses being out of whack, but suffers from an update delay problem where the toolbar shows the last-edited state of the tank (maybe some kind of race condition on the editor update call?)  Hopefully will be of some use.

Note the RealFuels section is totally untested.