Tweak the Luacheck configuration file and fix many warnings

.luacheckrc

@@ -1,14 +1,35 @@
+std = "lua51+minetest"
 unused_args = false
 allow_defined_top = true
+max_line_length = 999
 
-read_globals = {
-	"DIR_DELIM",
-	"minetest", "core",
-	"dump",
-	"vector", "nodeupdate",
-	"VoxelManip", "VoxelArea",
-	"PseudoRandom", "ItemStack",
-	"intllib",
-	"default",
+stds.minetest = {
+	read_globals = {
+		"DIR_DELIM",
+		"minetest",
+		"core",
+		"dump",
+		"vector",
+		"nodeupdate",
+		"VoxelManip",
+		"VoxelArea",
+		"PseudoRandom",
+		"ItemStack",
+		"default",
+		table = {
+			fields = {
+				"copy",
+			},
+		},
+	}
 }
 
+read_globals = {
+	"intllib",
+	"protector",
+	"isprotect",
+	"IsPlayerNodeOwner",
+	"HasOwner",
+	"getLastOwner",
+	"GetNodeOwnerName",
+}