Add luacheck

.luacheckrc

@@ -0,0 +1,18 @@
+max_line_length = 100
+
+read_globals = {
+	"DIR_DELIM",
+	"dump",
+	"VoxelManip", "VoxelArea",
+	"PseudoRandom", "ItemStack",
+	"AreaStore",
+	"default",
+	"intllib",
+}
+
+globals = {
+	"minetest",
+	"exchange_shop",
+}
+
+ignore = {"212/self"}