Abandon previous attempts to use matlab namespace...

for dseries (see 48115cb8, which does not work with Octave) or a
method (see ef923e41, which does not work with all supported Matlab's
versions) to initialize the dseries class.

src/@dseries/initialize.m → src/initialize_dseries_class.m

-function initialize(fake)
+function initialize_dseries_class()
 
 % Copyright (C) 2015-2019 Dynare Team
 %
@@ -16,7 +16,7 @@ function initialize(fake)
 % along with Dynare.  If not, see <http://www.gnu.org/licenses/>.
 
 % Get the path to the dseries toolbox.
-dseries_src_root = strrep(which('@dseries/initialize.m'),'@dseries/initialize.m','');
+dseries_src_root = strrep(which('initialize_dseries_class'),'initialize_dseries_class.m','');
 
 % Check that the x13 binary is available
 nox13 = false;

tests/runalltests.m

@@ -15,7 +15,7 @@ function runalltests()
 % You should have received a copy of the GNU General Public License
 % along with Dynare.  If not, see <http://www.gnu.org/licenses/>.
 
-dseries_src_root = strrep(which('runalltests'),'tests/runalltests.m','');
+dseries_src_root = []; % Will be updated by calling initialize_dseries_class().
 
 opath = path();
 
@@ -34,10 +34,10 @@ unit_tests_root = strrep(which('runalltests'),'runalltests.m','');
 
 % Initialize the dseries module
 try
-    dseries().initialize();
+    initialize_dseries_class();
 catch
     addpath([unit_tests_root '../src']);
-    dseries().initialize();
+    initialize_dseries_class();
 end
 
 warning off