Use refuel base cache in pathfinding.

See patch #4672


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@24862 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Renamed nations.ruleset entry allowed_city_styles as allowed_styles

See patch #4685


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@24865 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Remove the extra "'" in Spy must be Diplomat ruleset check's error message

See bug #22011

git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@24867 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Fixed checking if city can be the target of an action in AI code by
initializing variable.

See bug #22016


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@24869 a0f10bec-cc02-0410-94fc-a9cfff90b4cd