Add gives_income key to SLF

src/terrain/filter.cpp

@@ -107,6 +107,10 @@ bool terrain_filter::match_internal(const map_location& loc, const unit* ref_uni
 	if (cfg_.has_attribute("area") &&
 		fc_->get_tod_man().get_area_by_id(cfg_["area"]).count(loc) == 0)
 		return false;
+
+	if(cfg_.has_attribute("gives_income") &&
+		cfg_["gives_income"].to_bool() != fc_->get_disp_context().map().is_village(loc))
+		return false;
 
 	if(cfg_.has_attribute("terrain")) {
 		if(cache_.parsed_terrain == nullptr) {
@@ -548,6 +552,10 @@ void terrain_filter::get_locs_impl(std::set<map_location>& locs, const unit* ref
 			}
 		}
 	}
+	else if (cfg_["gives_income"].to_bool()) {
+		auto ar = fc_->get_disp_context().map().villages();
+		terrain_filterimpl::filter_xy(ar, match_set, *this, with_border);
+	}
 	else {
 		//consider all locations on the map
 		int bs = fc_->get_disp_context().map().border_size();