Added game_start AI callback.

See patch #4913


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@25486 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Added Trench and Airfield to civ2civ3 ruleset.

Patch by David Fernandez <bardo>

See patch #4608


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@25487 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Added capabilities string for xml-secfiles.

See patch #4915


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@25488 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Show ruleset description in server console after loading it.

See patch #4914


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@25489 a0f10bec-cc02-0410-94fc-a9cfff90b4cd