Add LuaCheck and GitHub workflow (#32)

.luacheckrc

@@ -0,0 +1,19 @@
+allow_defined_top = true
+unused_args = false
+max_line_length = false
+
+read_globals = {
+    string = {fields = {"split", "trim"}},
+    table = {fields = {"copy", "getn"}},
+
+    "player_monoids",
+    "playerphysics",
+    "hb",
+    "vector",
+    "hunger_ng",
+}
+
+globals = {
+    "minetest",
+    "hbhunger"
+}