Added dseries/end method.

Allows the following syntax to extract variables from a
dseries object ts:

us = ts{2:end};

matlab/@dseries/end.m

+function lastIndex = end(o, k, n)
+
+% Copyright (C) 2014 Dynare Team
+%
+% This file is part of Dynare.
+%
+% Dynare is free software: you can redistribute it and/or modify
+% it under the terms of the GNU General Public License as published by
+% the Free Software Foundation, either version 3 of the License, or
+% (at your option) any later version.
+%
+% Dynare is distributed in the hope that it will be useful,
+% but WITHOUT ANY WARRANTY; without even the implied warranty of
+% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+% GNU General Public License for more details.
+%
+% You should have received a copy of the GNU General Public License
+% along with Dynare.  If not, see <http://www.gnu.org/licenses/>.
+
+assert(k==1 && n==1, 'dseries::end: Wrong indexing!');
+lastIndex = o.vobs;
\ No newline at end of file