Merge pull request #2773 from samvdb/form_create_type_extension_fix_deprecated_call

[Cookbook][Form] Renamed getPropertyAccessor to createPropertyAccessor
Merge pull request #2777 from xabbuh/issue-2774

add missing code block
Merge branch '2.0' into 2.1
Merge branch '2.1' into 2.2

Conflicts:
	components/config/definition.rst
Merge branch '2.2' into 2.3

Conflicts:
	book/forms.rst
	book/installation.rst
	book/security.rst
	book/translation.rst
	components/config/definition.rst
	components/console/helpers/dialoghelper.rst
	components/process.rst
	cookbook/configuration/pdo_session_storage.rst
	cookbook/doctrine/registration_form.rst
	cookbook/form/inherit_data_option.rst
	cookbook/form/unit_testing.rst
	cookbook/routing/method_parameters.rst
	quick_tour/the_big_picture.rst
Merge branch '2.3'
Merge remote-tracking branch 'origin/master'
Removing note that used to be attached to a versionadded before it that was removed (and so this note should have been removed too)
Cookbook/Console/ConsoleCommand : Adding option/argument example in test

See comments in the PR #2792 I made on 2.1 branch
Adding a note to specify that parameter/option are not mandatory
Reference/forms/type/country : Minor bad copy/paste fix
Correct former TypeTestCase namespace
Reorganize and expand quickstart big picture docs on environments

* Add Environments section under "Understanding the Fundamentals" to introduce environments. This uses the glossary definition as a starting point and expands on it a little.
* Move the Web Profiler discussion out of Working with Environments into a separate section, and add a paragraph briefly summarizing what the profiler can do.
* Improve the Working with Environments section.
* Original changes from PR #2683 rebased on 2.2
added documentation for errorPath option of UniqueEntity constraint
added new line to errorPath documentation of UniqueEntity constraint
Some corrections of errorPath documentation for UniqueEntity constraint
fix xml service definition

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | 2.3
| Fixed tickets | n.a.
remove useless use of variable
Change to @Wouterj proposal which is better
Fixing mishandling (sorry)