added light source filter

cache.lua

@@ -283,7 +283,7 @@ function cache.fill_cache()
 							filter_result = {[filter_result] = true}
 						end
 						for key, val in pairs(filter_result) do
-							local filter_entry = key
+							local filter_entry = tostring(key)
 							if val ~= true then
 								filter_entry = filter_entry..":"..tostring(val)
 							end

classify_description_de.lua

@@ -80,6 +80,7 @@ return {
 	["vessel"] = { label = "Behälter" },
 	["eatable"] = { label = "Essbar" },
 	["shape"] = { label = "Geformt"},
+	["light"] = { label = "Lichtquelle"},
 
 	["tool"] = {label = false},
 	["tool:full_punch_interval"] = { label = "Verwendungsinterval" },

classify_description_en.lua

@@ -80,6 +80,7 @@ return {
 	["vessel"] = { label = "Vessel" },
 	["eatable"] = { label = "Eatable" },
 	["shape"] = { label = "Shaped"},
+	["light"] = { label = "Light source"},
 
 	["tool"] = {label = false},
 	["tool:full_punch_interval"] = { label = "Punch interval" },

filter.lua

@@ -98,6 +98,15 @@ filter.register_filter({
 		end
 	})
 
+filter.register_filter({
+		name = "light",
+		filter_func = function(def)
+			if def.light_source and def.light_source ~= 0 then
+				return def.light_source
+			end
+		end
+	})
+
 filter.register_filter({
 		name = "vessel",
 		filter_func = function(def)