mapinfo: fix and rename noautomaplist flag to donotwant

mapinfo: fix and rename noautomaplist flag to donotwant

This flag was ignored in the code paths used on most servers, and its
name and behaviour were not ideal for its intended use, see
7d48e976c8a9b3f80350b2ad41d9feec2797cf76 description which seems clear
that it's for allowing a certain kind of map to be available on the
server but not be included in the usual voting pool.

This updated implementation omits the flagged maps from GUI voting and
prevents them being selected by other GotoNextMap()/GetNextMap() code
paths, unless there aren't enough viable maps in which case they
can still be used as fallbacks.

The flagged maps are always listed in CLI and may be nominated with
`suggestmap` or vcalled with `gotomap` or `nextmap`.