Fixed an apparent bug in madlib.arima

because arima output format changed
Made - work for time types
Small updates
Made db.obj - db.obj work for time types
Corrected typos
Made e2 - e1 work, not trivial
Fixed bugs
Added support for + methods of time types

Still need the support for arrays

Also need to support + method for db.obj,db.obj
Enabled max, min for time types
Fixed a bug for +