[Freeciv-Dev] (PR#2437) new graphics: improvements and technology

["Jason Short via RT" <rt@xxxxxxxxxxxxxx>]

Another problem: this change needs to be backwards-compatible with
unsupporting rulesets.  For instance if I do "civserver -r civ2.serv" I
shouldn't get a server crash - it should just not have the graphics.  So
instead of secfile_lookup_str you should use secfile_lookup_str_default
at the server end.

Oh, and we should add support to the civ1 and civ2 rulesets, where possible.

jason