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.