model/airport: Added static by_bbox() method
model/airport: Added static by_bbox() method

Turbo87/skylines,shadowoneau/skylines,skylines-project/skylines,RBE-Avionik/skylines,RBE-Avionik/skylines,snip/skylines,snip/skylines,TobiasLohner/SkyLines,Harry-R/skylines,Harry-R/skylines,Harry-R/skylines,snip/skylines,kerel-fs/skylines,Turbo87/skylines,Harry-R/skylines,skylines-project/skylines,shadowoneau/skylines,RBE-Avionik/skylines,kerel-fs/skylines,TobiasLohner/SkyLines,Turbo87/skylines,Turbo87/skylines,skylines-project/skylines,shadowoneau/skylines,RBE-Avionik/skylines,kerel-fs/skylines,skylines-project/skylines,shadowoneau/skylines,TobiasLohner/SkyLines