[ci skip] Changed 'first argument' to '+name+ argument'

`#create!` regarding validations in contrast to the behavior of
`#create`. Also describe creating multiple objects using an array of
hashes as the +attributes+ parameter. [ci skip] /cc #16384

[ci skip] Added +object+ and +attributes+ to create! description for rdoc

Pull spring gem entry into the Gemfile template instead of gemfile_entries so it can be grouped with the other development tools

remove dead file_watcher code

Tables existence check query is executed in large quantities

Closes #16422

When Rails starts, tables existence check query is executed
number of models.
In case of mysql,

    SHOW TABLES LIKE 'table1';
    SHOW TABLES LIKE 'table2';
    SHOW TABLES LIKE 'table3';
    ...
    SHOW TABLES LIKE 'table999';

Add process to get the names of all tables by one query.

Fix in has_secure_password for passwords containing only spaces.

Remove ActionController::RaiseActionExceptions.

The latest modification to the code was done in https://github.com/rails/rails/commit/5e3517ea. In Rails 3.2,
`ActionController#rescue_action` was deprecated and `rescue_action_without_handler` is no longer being used.

Currently when we call id_was and we have a custom primary key name
Active Record will return the current value of the primary key. This
make impossible to correctly do an update operation if you change the
id.

Fixes #16413

See
https://github.com/rails/turbolinks/commit/153f1b0f04c718442cfd73365a2778dfe1a1c5c7

Fixes #16406

this means we can meaningfully override methods in the subclass

So this trick is not needed to be documented anymore.

Fixed #select form builder helper to support block without html output

Add an after_bundle callback in Rails templates

Conflicts:
	railties/CHANGELOG.md

purge database before loading schema, take 2

The rake tasks and the `DatabaseTakss` adapter classes used to
assume a configuration at some places. This forced the rake
tasks to establish a specific connection before calling into
`load_schema`.

After #15394 this started to cause issues because it could
`purge` the wrong database before loading the schema.

Revert "Revert "Merge pull request #15394 from morgoth/fix-automatic-maintaining-test-schema-for-sql-format""

This reverts commit 5c87b5c5.

if we access the instance, we can free up lots of codes

especially if you're just going to add a call two lines down that
populates the cache. common.

Clarify Transaction responsibilities by breaking unneeded inheritance hierarchy.