Returns a string giving the version number of the MOO server in the following
format:
"<major>.<minor>.<release>"
where <major>, <minor>, and <release> are all decimal numbers.
The major version number changes very slowly, only when existing MOO code might
stop working, due to an incompatible change in the syntax or semantics of the
programming language, or when an incompatible change is made to the database
format.
The minor version number changes more quickly, whenever an upward-compatible
change is made in the programming language syntax or semantics. The most
common cause of this is the addition of a new kind of expression, statement, or
built-in function.
The release version number changes as frequently as bugs are fixed in the
server code. Changes in the release number indicate changes that should only
be visible to users as bug fixes, if at all.