use Variable.offset to order LOCAL variables

previously, this was only used for attr order in Entity's

these two uses should not conflict
when pretty-printing, order LOCAL vars the same way as in source file
put each SUBTYPE/SUPERTYPE on its own line, indent ONEOF
Don't aggressively wrap SUBTYPEs - leave as before
Merge pull request #286 from stepcode/review/exppp_var_order

preserve EXPPP variable order