Fixed a crash when ruleset provides no suitable pollution or fallout for a tile
selected to get such an extra.

See bug #21949


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@24801 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Fixed construction of final URL when .modpack gives relative one.

See bug #21951


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@24802 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Add "Team" requirement range.

See gna patch #4388.

git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@24803 a0f10bec-cc02-0410-94fc-a9cfff90b4cd