Use fc_tristate in meta knowledge and remove mk_eval_result.

See patch #4517

git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@24527 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Itnroduced the concept of nation styles. In this initial commit they are just loaded from
the ruleset data and passed to client, not used for anything.

See pacyh #4511


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@24528 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Meta knowledge: Don't ask for the type of the target unit if it is NULL.

Asking for the unit type of NULL causes an assertion failure.

See bug #21694

git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@24529 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Find the probability of success for each possible spy action on the server.

Make the client ask for them right before they are needed. This way results
won't get outdated while waiting for the players attention in a queue.

The client no longer use meta knowledge.

Requested by Jacob Nevins <jtn@gna>

See patch #4200

git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@24530 a0f10bec-cc02-0410-94fc-a9cfff90b4cd