Added test_all.
Renaming.
Removed prec_add
Modified __pow__ and __mul__ method of modular forms.
Modified methods _to_format_dct and _from_dict_to_object.
Modified method  __init__ of Deg2ModularFormQseries.
Added attribute _is_gen. Let generators' base_ring to be ZZ.
Added test/test_save_load.py.