format to ensure correct comparison of scale denominators against map
scale and filters against features. Introduces a new
OpenLayers.String.numericIf function. r=fredj,tschaub (closes#1874)
git-svn-id: http://svn.openlayers.org/trunk/openlayers@8927 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf