Part masses

this PR resolves #456.

    It adds to PART

:MASS
:DRYMASS
:WETMASS
:HASPHYSICS //this was important to the calculation so i decided to expose it

    It adds to SHIP

:DRYMASS
:WETMASS
:TYPE //should have be a different PR but i got carried away

You should now be able to change craft names and types in kerboscript.

    
**The above comment brings to mind a big question I have that I noticed before but forgot to ask about:**

What is the order of operations when using the newer AddSuffix technique on a structure class derived from another structure class?  In the older technique, each *GetSuffix()* would contain a call to *base.GetSuffix()* at the BOTTOM of it, if and only if it failed to find the suffix string in its own cases.  This ensured that the "more derived" suffix would override the "more base" one if there was a name clash between them.  But now... is there a guarantee that when I call SHIP:LATITUDE that I don't end up calling Orbitable's :LATITUDE instead of Vessel's :LATITUDE?  With Latitude it doesn't matter because it's the same number either way - but in some cases ensuring you get the derived instead of the base version might be more important.  As it stands, when it chucks both the derived and the base suffixes together into a single hash lookup dictionary, do we have any guarantee about which one will "win" when the two clash with the same name?