stopClick is true, clicks handled by the feature handler don't propagate to
other click listeners; otherwise handled clicks do propagate. The same kind of
rule applies to stopDown and stopUp. These properties default to true. Thanks
to Attila Csipa for expressing the need for this feature and cooking up the
first patch. r=tschaub. (closes#1266)
git-svn-id: http://svn.openlayers.org/trunk/openlayers@5976 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf