Corrected interpretation of return value of can_unit_attack_ -family of functions
causing server crash and other problems.

Reported by Christian Knoke <chrisk>, debugged by Jacob Nevins <jtn>

See bug #21693


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@24564 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Give random offset to add to citizen slot in city dialog to avoid always
using same icon as the first one if there's multiple defined for a citizen type.

See patch #4516


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@24567 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Added cumulative kind of culture; History

See patch #4020


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@24568 a0f10bec-cc02-0410-94fc-a9cfff90b4cd