added getLineNumberAtCursor() method to ZString.

ZString.h

@@ -438,6 +438,13 @@ namespace coreutils {
       ///
 
       ZString removeTrailingZeros();
+
+      ///
+      /// Returns the number of line termination characters + 1 based upon
+      /// the cursor position.
+      ///
+
+      int getLineNumberAtCursor();
       
     protected:
       char *data;