Converts time sries into a tsmat
tsm=ts2tsmat(arg1,...,argn)
* argi = time series, the string 'cte' or 'const' vectors or matrices that have the same # of rows, itself equal to the # of time periods matched by the ts
* tsm = a tlist of type tsmat
ts1=reshape([1:10],'1a'); ts2=reshape(2*[1:10],'1a'); tsmat1=ts2tsmat('ts1','ts2');