Added initial version of set_map_zoom() function.

See patch #4619


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@24711 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Do not free info label surface while it's still going to be used. Fixes also
double free crash when it finally is time to free it.

See patch #4620


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@24712 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Use present = FALSE requirements instead of nreqs vector in civ2 ruleset
effects.ruleset.

See patch #4621


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@24713 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Save client options file inside .freeciv -directory.

See patch #4387


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@24714 a0f10bec-cc02-0410-94fc-a9cfff90b4cd