Add argcargv.i to Lua

Found in https://stackoverflow.com/questions/9860362/swig-lua-call-mint-argv-char-argc

Lib/lua/argcargv.i

@@ -0,0 +1,58 @@
+/* ------------------------------------------------------------
+ * --- Argc & Argv ---
+ * ------------------------------------------------------------
+ *
+ *  Use it as follow:
+ *
+ *    %apply (int ARGC, char **ARGV) { (size_t argc, const char **argv) }
+ *    extern int mainApp(size_t argc, const char **argv);
+ *
+ *  then in the lua:
+ *
+ *    args = { "arg0", "arg1" }
+ *    mainApp(args);
+ *
+ * ------------------------------------------------------------ */
+
+%{
+SWIGINTERN int SWIG_argv_size(lua_State* L, int index) {
+  int n=0;
+  while(1){
+    lua_rawgeti(L,index,n+1);
+    if (lua_isnil(L,-1))
+      break;
+    ++n;
+    lua_pop(L,1);
+  }
+  lua_pop(L,1);
+  return n;
+}
+%}
+
+%typemap(in) (int ARGC, char **ARGV) {
+  if (lua_istable(L,$input)) {
+    int i, size = SWIG_argv_size(L,$input);
+    $1 = ($1_ltype) size;
+    $2 = (char **) malloc((size+1)*sizeof(char *));
+    for (i = 0; i < size; i++) {
+      lua_rawgeti(L,$input,i+1);
+      if (lua_isnil(L,-1))
+   break;
+      $2[i] = (char *)lua_tostring(L, -1);
+      lua_pop(L,1);
+    }
+    $2[i]=NULL;
+  } else {
+    $1 = 0; $2 = 0;
+    lua_pushstring(L,"Expecting argv array");
+    lua_error(L);
+  }
+}
+
+%typemap(typecheck, precedence=SWIG_TYPECHECK_STRING_ARRAY) (int ARGC, char **ARGV) {
+  $1 = lua_istable(L,$input);
+}
+
+%typemap(freearg) (int ARGC, char **ARGV) {
+  free((char *) $2);
+}