add .luacheckrc and gh action

.luacheckrc

@@ -0,0 +1,30 @@
+
+globals = {
+	"mesecon",
+	"minetest"
+}
+
+-- ignore unused vars
+unused = false
+
+read_globals = {
+	-- Stdlib
+	string = {fields = {"split"}},
+	table = {fields = {"copy", "getn"}},
+
+	-- Minetest
+	"vector", "ItemStack",
+	"dump", "VoxelArea",
+
+	-- system
+	"DIR_DELIM",
+
+	-- deps
+	"default", "screwdriver"
+}
+
+ignore = {
+	"631", -- line too long
+	"621", -- inconsistent indendation
+	"542", -- empty if branch
+}