General Functions for estimation

• bounds — setting estimation bounds
• explolist — splitting of a list
• explon — explosion of several sequences of variables
• explone — explosion of one sequence of variables
• explots — explosion of a list of ts
• explouniv — explosion of a sequence of variables
• explovars — explosion of a sequence of variables
• lagbounds — lag bounds in a regression
• res2ts — result vector object to timeseries