Incrementing the RPG format version number

The RPG Version number (see GEN) is used to provide forwards compatibility warning messages when someone opens a new RPG file in an old copy of Game or Custom.

In the past, the version number was used to trigger format changes in the upgrade() routine, but this has been depreciated, and format changes are now done using FIXBITS.BIN or BINSIZE.BIN (and in the future also with RELOAD)

The RPG version number should be incremented whenever a change could lead to data loss if a game is edited with an older copy of Custom or is otherwise likely to appear broken -- probably several times per release cycle. (This is a recent change to policy, and we don't actually remember to do it very often.)

Of course, it's always best to use a version of Game at least as recent as the version of Custom with which the game was edited, but this feature doesn't ensure that.