add luacheck and integration test workflows / fix luacheck errors

partially attends to https://github.com/pandorabox-io/pandorabox.io/issues/444 (the ObjectRef issue)

.luacheckrc

@@ -0,0 +1,34 @@
+
+unused_args = false
+
+globals = {
+	"wieldview",
+	"armor",
+	"armor_i18n",
+	"inventory_plus"
+}
+
+read_globals = {
+	-- Stdlib
+	string = {fields = {"split"}},
+	table = {fields = {"copy", "getn"}},
+
+	-- Minetest
+	"vector", "ItemStack",
+	"dump", "VoxelArea",
+
+	-- deps
+	"default",
+	"minetest",
+	"unified_inventory",
+	"intllib",
+	"wardrobe",
+	"player_monoids",
+	"armor_monoid",
+	"sfinv",
+	"ARMOR_MATERIALS",
+	"ARMOR_FIRE_NODES",
+	"pova",
+	"skins",
+	"u_skins"
+}