Changed ActiveRecord::Associations::CollectionProxy#select to take multiple arguments.

This makes the arguments the same as ActiveRecord::QueryMethods::select.
Maintain proleptic gregorian in Time#advance

Time#advance uses Time#to_date and Date#advance to calculate a new date.
The Date object returned by Time#to_date is constructed with the assumption
that the Time object represents a proleptic gregorian date, but it is
configured to observe the default julian calendar reform date (2299161j)
for purposes of calculating month, date and year:

  Time.new(1582, 10, 4).to_date.to_s           # => "1582-09-24"
  Time.new(1582, 10, 4).to_date.gregorian.to_s # => "1582-10-04"

This patch ensures that when the intermediate Date object is advanced
to yield a new Date object, that the Time object for return is contructed
with a proleptic gregorian month, date and year.
Allows you to check if an attribute has changed to a particular value

model.name_changed?(from: "Pete", to: "Ringo")
[ci skip] trailing documentation whitespace
fix quoting non-strings

Closes #13444
Merge pull request #13451 from dmathieu/quoting_non_strings

Fix typecasting array of integers
CHANGELOG entry for #13451. [ci skip]
Add missing av/railtie require
Merge pull request #13457 from strzalek/add-missing-av-railtie

Add missing av/railtie require
added test cases for Resolver#connection_url_to_hash
Merge pull request #13446 from kuldeepaggarwal/resolver-test-cases

Resolver test cases
On destroying do not touch destroyed belongs to association.

Fixes: #13445
Merge pull request #13455 from jetthoughts/13445_fix_touch_destroyed_record

On destroying do not touch destroyed belongs to association.
Fix comment example in AR enum [ci skip]
Tell how to Create a Database in Error Message

Currently if you attempt to use a database that does not exist  you get an error:

```
PG::ConnectionBad FATAL:  database "db_error" does not exist
```

The solution is easy, create and migrate your database however new developers may not know these commands by memory. Instead of requiring the developer to search for a solution, tell them how to fix the problem in the error message:

```
ActiveRecord::NoDatabase: FATAL:  database "db_error" does not exist
Run `$ bin/rake db:create db:migrate` to create your database
```

Active Record should not know about `rake db:migrate` so this additional information needs to come from the railtie. Potential alternative implementation suggestions are welcome.
Merge pull request #13427 from schneems/schneems/cannot-connect-postgres-error

Tell how to Create a Database in Error Message
[ci skip] a destroy action in controller, not delete [getting_stated.md].
Do not store production information in .yml files

Instead, read information from environment variables.
Merge pull request #13462 from JuanitoFatas/getting-started

[ci skip] a destroy action in controller, not delete [getting_stated.md].
Move the null mime type to request.format

TLDR: always return an object that responds to the query methods from
request.format, and do not touch Mime::Type[] lookup to avoid bugs.

---

Long version:

The initial issue was about being able to do checks like
request.format.html? for request with an unknown format, where
request.format would be nil.

This is where the issue came from at first in #7837 and #8085
(merged in cba05887dc3b56a46a9fe2779b6b228880b49622), but the
implementation went down the path of adding this to the mime type
lookup logic.

This unfortunately introduced subtle bugs, for instance in the merged
commit a test related to send_file had to be changed to accomodate the
introduction of the NullType.

Later another bug was found in #13064, related to the content-type being
shown as #<Mime::NullType:...> for templates with localized extensions
but no format included. This one was fixed in #13133, merged in
43962d6ec50f918c9970bd3cd4b6ee5c7f7426ed.

Besides that, custom handlers were not receiving the proper template
formats anymore when passing through the rendering process, because of
the NullType addition. That was found while migrating an application
from 3.2 to 4.0 that uses the Markerb gem (a custom handler that
generates both text and html emails from a markdown template).

---

This changes the implementation moving away from returning this null
object from the mime lookup, and still fixes the initial issue where
request.format.zomg? would raise an exception for unknown formats due to
request.format being nil.