Skip test_migrate_revert_add_index_with_name for some databases

do not allow to create duplicate indexes on the same columns

We noticed the rails gem increased in size between the beta and rc
versions, and the reason is that some guides images were updated but not
properly optimized, and one image changed from png to jpg, way bigger.

Converting the jpg image back to png, and using ImageOptim to optimize
all the images for web view, improves the situation [ci skip].

---

In current master/4-1-stable:

    508K  guides/assets/images/getting_started/

In v4.1.0.beta1:

    268K  guides/assets/images/getting_started/

In 4-0-stable

    328K  guides/assets/images/getting_started/

After the patch:

    260K  guides/assets/images/getting_started/

Add missing parantheses in index_exists?

Remove 4-1 related entries from master [ci skip]

See 449039a8 for the original commit.

Sungularize ActionController::UnpermittedParameters error in case when only 1 parameter is unpermitted.

Standardized punctuation.

[skip ci] Fixing typo in documentation: actionview/lib/action_view/helpers/url_helper.rb

This is a follow up to #14170. While backporting I recognized
that this call is not needed at all.

there could be more than 10 nested records

Go with #presence_in instead of #present_in -- it doesnt sound quite as good, but the closer relationship to #presence over #present is ultimately worth it

Simple Sungularize ActionController::UnpermittedParameters error in case when only 1 parameter is unpermitted.

This is a follow up to #13515. It includes the name given and
the singularized version in the warning message. This will aide the user
to see wether the detected singular was right or not.

coerce strings when reading attributes

Extract local cache middleware

Extract LocalCache Middleware, so it can requires rack dependencies,
without adding rack dependencies to `AS::Cache::Strategy::LocalCache`.

Dynamically define PostgreSQL Range OIDs

The Ruby Range object does not support excluding beginnings.
We currently support excluding beginnings for some subtypes using
manually by incrementing them (now using the `#succ` method).
This is approach is flawed as it's not equal to an excluding beginning.

This commit deprecates the current support for excluding beginnings.
It also raises an `ArgumentError` for subtypes that do not implement the `succ`
method.

This is a temporary solution to get rid of the broken state. We might still
add complete support for excluding beginnings afterwards. (Probably with a
new `PGRange` object, which acts like a `Range` but has excluding beginnings.

This gets AR working with custom defined range types. It also
removes the need for subtype specific branches in `OID::Range`.

This expands the interface of all `OID` types with the `infinity` method.
It's responsible to provide a value for positive and negative infinity.

See #13875

Added warning when user tried to create model with pluralize name.

  1. Generate model with correct_name.
  2. It will help new users to avoid mistakes when tried to create model with wrong name.

Fixed typo in comment about MAX_ID.

Distinguish ConnectionNotEstablished messages: no conn pool for the class, or no conn available from the pool

Prevent foreign_key_for? from evaluating all attributes

This reverts commit e0a521cf.

Conflicts:
	railties/CHANGELOG.md

We expect loggers to quack like stdlib logger. If log4r needs different
level= assignment, using a Logger-quacking wrapper is the way to do it.

Fixes #14114.