save_base() alters data, and can be called from templates

[Marty Alchin]

In [7221], save() was changed to just be a call to save_base(), making subclassing easier, but the alters_data attribute never made it onto save_base(). Since save_base() can (and usually is) called without arguments, this means that templates that receive an object can use {{ obj.save_base }} and commit to the database, when that shouldn't be allowed.

[Marty Alchin]

Added alter_data to Model.save_base()

[Gary Wilson]

(In [7526]) Fixed #7212 -- Added alters_data attribute to Model.save_base method, thanks Gulopine.