twnlua: partial impl for return propagation, input now works

share/twn_api.json

@@ -4,7 +4,7 @@
     "procedures": {
         "input_action": {
             "module": "input",
-            "symbol": "bind_action",
+            "symbol": "action",
             "header": "twn_input.h",
             "params": [
                 { "name": "name", "type": "char *" },