check project code style. add .luacheckrc (#7)

.luacheckrc

@@ -0,0 +1,51 @@
+std = "max"
+files['.luacheckrc'].global = false
+unused_args = false
+
+max_code_line_length = 90
+max_comment_line_length = false
+
+globals = {
+  "sys",
+  "go",
+  "gui",
+  "label",
+  "render",
+  "crash",
+  "sprite",
+  "sound",
+  "tilemap",
+  "spine",
+  "particlefx",
+  "physics",
+  "factory",
+  "collectionfactory",
+  "iac",
+  "msg",
+  "vmath",
+  "url",
+  "http",
+  "image",
+  "json",
+  "zlib",
+  "iap",
+  "push",
+  "facebook",
+  "hash",
+  "hash_to_hex",
+  "pprint",
+  "init",
+  "final",
+  "update",
+  "on_input",
+  "on_message",
+  "on_reload",
+  "socket",
+  "table",
+  "debug",
+  "timer",
+  "window",
+  "buffer", 
+  "resource",
+  "defos",
+}