Moved isweekly, ismonthly, isquaterly and isyearly routines from...

Moved isweekly, ismonthly, isquaterly and isyearly routines from matlab/@dynSeries/private to matlab/utilities/dates. Adapted dynare_config conformably to these changes.

matlab/dynare_config.m

@@ -59,6 +59,7 @@ addpath([dynareroot '/gsa/'])
 addpath([dynareroot '/ep/'])
 addpath([dynareroot '/utilities/doc/'])
 addpath([dynareroot '/utilities/tests/'])
+addpath([dynareroot '/utilities/dates/'])
 addpath([dynareroot '/utilities/dataset/'])
 addpath([dynareroot '/utilities/general/'])