Metaknowledge for Terrain, TerrainFlag, TerrainClass, Resource, Extra, BaseFlag and RoadFlag

See patch #4996

git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@25748 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Only append requirements to action enablers when loading the rules to play

Reported by Emmet Hikory <persia> and Marko Lindqvist <cazfi>

See bug #22401

git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@25749 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Fixed reversed base buildability check in can_build_extra_base()

See bug #22398


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@25750 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Fixed the way AI handles negative building want's effect to tech want.

See bug #22399


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@25751 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Do not use specialist name in entry name, only as value, in savegame format.

See bug #22378


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@25754 a0f10bec-cc02-0410-94fc-a9cfff90b4cd