Changed behaviour of @dseries/pop method. If only one argument is provided,...

Changed behaviour of @dseries/pop method. If only one argument is provided, remove the last variable.

matlab/@dseries/pop.m

@@ -45,11 +45,18 @@ function [ts,id] = pop(ts,a) % --*-- Unitary tests --*--
 % You should have received a copy of the GNU General Public License
 % along with Dynare.  If not, see <http://www.gnu.org/licenses/>.
 
-id = find(strcmp(a,ts.name));
+if nargin<2
+    % Removes the last variable
+    id = ts.vobs;
+else
+    id = find(strcmp(a,ts.name));
+end
+
 if isempty(id)
     id = 0;
     return
 end
+
 ts.vobs = ts.vobs-1; 
 ts.data(:,id) = [];
 ts.name(id) = [];