explosion of a sequence of variables
[namexos,listts,vecy,indts,ndvec,indcte,nvar,listtsmat,indtsmat]=explovars(names,defname)
* names = either
- a list of variables, each element could be a timeseries, a real vector, a real matrix or a string (the name of a variable with one of the types cited above, between quotes)
- a matrix of strings, each one being the name of a variable
- the string 'cte', 'const' or 'trend^p'
* defname = default name of variables
* namexos = a (k x 1) string vector
* listts = a list of ts
* vecy = a (n x k) matrix of real values
* indts = a (k1 x 1) vector of integers that indicates the indexes of the ts in the original list
* indvec = a (k2 x 1) vector of integers that indicates the indexes of the real vectors in the original list
* indcte = a (k3 x 1) vector of integers that indicates the indexes of the terms 'cte' or 'const' in the original list
* nvar = # of variables in the list
* listtsmat = a list of tsmat
* indtsmat = a (k4 x 1) vector of integers that indicates the indexes of the tsmat in the original list