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BUG Hardcoded project name in include_by_locale()

include_by_locale() should not use hardcoded default project name 'mysite' (fixes #7969).
BUG removeRequiredField() should use array_splice() instead of unset()

Function unset() preserves numeric keys and method removeRequiredField() will give a PHP notice about nonexistent array key and loop won't iterate throughout all elements in array on second method call (and all subsequent).
So it's better to use foreach loop and array_splice() function (it doesn't preserve numeric keys).
BUG Calling DataObject::relField() on a object with an empty relation list

This causes a 'Fatal error: Call to a member function hasMethod() on a non-object'.

This can happen when displaying a field in a gridfield on a belongs_to relationship.
Set 'active' correctly for accordion widget

The accordion widget was previously being passed true and false, where as it either expects true or the integer of the panel to show.

This fix sets it as either false or 0.
Update forms/TextareaField.php

small edit to description of the field (usage).  Removed reference to cols and rows parameters. 
adding extension hook in GridFieldDetailForm.php

This hook is useful so that you can add additional fields / actions in a gridfield form that are not available in other settings (e.g. additional actions: previous / next / save and publish / unpublish / etc
NEW: Add ReadonlyField::setIncludeHiddenField()

The new config setter restores the 2.4 behaviour of including <input type="hidden"> with a field. Although as a default, this option has security flaws; it is useful in a few circumstances and, if nothing else, is handy to make upgrading sites easier.
BUGFIX: Don't clear form messages unless forTemplate() is actually called.
BUGFIX: Clear session-stored form data as well as form error message.
BUGFIX: Added X-Forwarded-Protocol and User-Agent to Vary header.
NEW: Improve HTTP caching logic to automatically disable caching for requests that use the session.

This improvement makes it easier to set a side-wide default cache time without needing to worry about CSRF-protected forms, etc.
FIX: Fix issue with not being able to log out on Chrome when caching enabled because of Chrome bug
FIX: Fix DataObject::get_one() when the classname is passed with improper casing.
Merge pull request #1090 from sminnee/fix-get-one-case

FIX: Fix DataObject::get_one() when the classname is passed with imprope...
Merge pull request #1080 from sminnee/caching-improvements

Caching improvements
Merge pull request #1082 from sminnee/form-improvements

Form improvements
Merge pull request #1071 from sunnysideup/patch-1

Update forms/TextareaField.php: small edit to description of the field
Merge pull request #1072 from sunnysideup/patch-2

adding extension hook in GridFieldDetailForm.php
Merge pull request #1056 from kopymark/patch-2

BUG: Accordion widget doesn't actually accept 'true' for 'active'
Merge pull request #1051 from uniun/patch-3

BUG removeRequiredField() should use array_splice() instead of unset()