Correct handling of dy (or absence thereof) in ftv

pub/CHANGELOG

@@ -2,6 +2,7 @@ Release 2.3.6a of :
 
 - Bug fixes:
   - Restored ability to load files from outside the current working directory
+  - Correct handling of dy (or absence thereof) in ftv
 - New functionality:
   - Frida main program now has command-line options -b, -h, --version
   - Command crp to restrict plot range

pub/lib/import.cpp

@@ -186,9 +186,9 @@ void NImport::read_tab(string qualif)
                             + " exactly " + S(with_d ? 3 : 2) + " are required";
                     }
                     if (with_d)
-                        s->push_xy(dat[0], dat[1]);
-                    else
                         s->push_xyd(dat[0], dat[1], dat[2]);
+                    else
+                        s->push_xy(dat[0], dat[1]);
                 }
             }
             ++nline;