A3 Duration

- When parsing duration literals, look-ahead now prevents an ordinal
  such as '31st' (August 31st) from being interpreted as two tokens
  '31s' (duration) and 't' (word).  This is the same fix that was
  applied to A3::is_number.  I'll be there are more that I missed.

src/A3.cpp

@@ -1456,6 +1456,9 @@ bool A3::is_dom (Nibbler& n, std::string& result)
 }
 
 ////////////////////////////////////////////////////////////////////////////////
+// A duration may only be followed by '\0', ')' or ' '.
+//
+// This prevents the interpretation of '31st' as a duration ('31s').
 bool A3::is_duration (Nibbler& n, std::string& result)
 {
   n.save ();
@@ -1468,8 +1471,14 @@ bool A3::is_duration (Nibbler& n, std::string& result)
   if (n.getInt (quantity) &&
       n.getOneOf (units, unit))
   {
-    result = format (quantity) + unit;
-    return true;
+    char next = n.next ();
+    if (next == '\0' ||
+        next == ')'  ||
+        next == ' ')
+    {
+      result = format (quantity) + unit;
+      return true;
+    }
   }
 
   n.restore ();