RX: Was missing REG_ENHANCED, which omits \d support

src/RX.cpp

@@ -56,7 +56,7 @@ void RX::compile ()
 
     int result;
     if ((result = regcomp (&_regex, _pattern.c_str (),
-                           REG_EXTENDED | REG_NEWLINE |
+                           REG_ENHANCED | REG_EXTENDED | REG_NEWLINE |
                            (_case_sensitive ? 0 : REG_ICASE))) != 0)
     {
       char message[256];

test/rx.t.cpp

@@ -34,7 +34,7 @@ Context context;
 
 int main (int argc, char** argv)
 {
-  UnitTest ut (23);
+  UnitTest ut (24);
 
   // Ensure environment has no influence.
   unsetenv ("TASKDATA");
@@ -119,6 +119,10 @@ int main (int argc, char** argv)
   ut.ok (r12.match (text), text + " =~ /\\bthe\\b/");
 #endif
 
+  text = "D0";
+  RX r13 ("D\\d");
+  ut.ok (r13.match (text), text + " =~ /D\\d/");
+
   return 0;
 }