don't convert mailer default values to procs

Invoke mailer defaults as procs only if they are procs, do not convert
with to_proc.  That an object is convertible to a proc does not mean it's
meant to be always used as a proc.  Fixes #11533
extract mutation from generation method
factory methods should not have side effects.

Move model mutation to the methods that are called on the model.
Use GeneratedAttribute#column_name if #reference? scaffold_generator in _form view [Fixes #11573]
add a specific factory method rather than using new
stop relying on side effects of const_missing
Fix secure_password password_confirmation validations
Merge pull request #11107 from nettsundere/password-confirmation-fix

Fix secure_password password_confirmation validations
acually get the actual source reflection :cry::gun:
eliminate conditional in JoinHelper
oops!
Refactor to use flat_map
text_area should handle nil value option like text_field
Simplify select_one method.

The select_all method always returns ActiveRecord::Result instance,
and the ActiveRecord::Result includes Enumerable mixin.
If #empty?, #first method returns nil. Thus we can simplify this method.
Fix indentation.
Merge pull request #11570 from joelcogen/harmonize_text_field_and_area

text_area should handle nil value option like text_field
Merge pull request #11579 from kennyj/refactor_20130724

Simplify select_one method.
Merge pull request #11559 from bughit/11533_to_proc

don't convert mailer default values to procs
AM Guide: Should be "different formats".
Cleanup task for informing about hstore