Add: get_on_of returns index of one of those keys.

keys are uppercased, so make sure they are all upper.
return is index (0-...), < 0 = timeout.

door.cpp

@@ -930,6 +930,32 @@ std::string Door::input_string(int max) {
   }
 }
 
+/**
+ * @brief Get one of these keys
+ *
+ * returns offset, or < 0 if timeout.
+ *
+ * @param keys
+ * @return int
+ */
+int Door::get_one_of(const char *keys) {
+  int c;
+  while (true) {
+    c = sleep_key(inactivity);
+    if (c < 0)
+      return c;
+
+    if (c > 0x1000)
+      continue;
+    char *key = strchr(keys, (char)toupper(c));
+    if (key != nullptr) {
+      return key - keys;
+    }
+    *this << '\x07';
+  }
+  return c;
+}
+
 /**
  * Take given buffer and output it.
  *

door.h

@@ -261,6 +261,7 @@ public:
   int get_input(void);
   signed int sleep_key(int secs);
   std::string input_string(int max);
+  int get_one_of(const char *keys);
 };
 
 // Use this to define the deprecated colorizer  [POC]