-Codechange: removed next_in_chain_old, and saved ->next for Vehicles
(and bumped savegame revision for that to version 4.4)
-Codechange: Added _sl.full_version, which has both major and minor version
an uint8 till the savegame version is bumped to version 5. Then it works
automaticly as a fully uint16. So _stations[] can not be increased till
after the bump!!
-Fix: added debug code to autosave cause it is buggy in multiplayer (does not remember settings; takes them from _opt instead of _new_opt (or vice versa)).
