Enhanced exception printing, with fprintf style messages

Signed-off-by: Nicola Vigano <nicola.vigano@esrf.fr>

zUtil_ErrorHandling/gtPrintException.m

-function [varargout] = gtPrintException(ex, errorMessage)
-% gtPrintException(ex, errorMessage)
-% prints the exception information
+function [varargout] = gtPrintException(ex, varargin)
+% gtPrintException(ex, varargin)
+% prints the exception information, where varargin is the error message and is
+% passed to sprintf
 
     outString = sprintf('\n');
-    if (exist('errorMessage', 'var'))
-        outString = [outString sprintf(['--> ' errorMessage ' <-- Error:\n'])];
+    if (nargin > 1)
+        outString = [outString '--> ' sprintf(varargin{:}) ' <-- Error:' sprintf('\n')];
         outString = [outString print_exception(ex)];
     else
         outString = [outString sprintf('-- Error:\n')];