ensure that length and size are run in the test suite

src/@dseries/length.m

-function length(o)
+function length(o) % --*-- Unitary tests --*--
 
 % Overloads size function.
 

src/@dseries/size.m

-function varargout = size(o, varargin)
+function varargout = size(o, varargin) % --*-- Unitary tests --*--
 
 % Overloads size function.