Added the possibility to overwrite the time and init member of a dynSeries object (not allowed for freq, nobs and vobs).

(cherry picked from commit b0d6e2b7b62809343dc685485f75b0f71070c245)
Added unitary tests.

(cherry picked from commit 667e3085851273339c55bffdeda84ae6b9041209)
data, name and tex of the dynSeries class are also private members that cannot be overwritten.

(cherry picked from commit 609f94881f33e857811cbfe86c9419a71d806b87)