Merge pull request #1987 from richardmiller/updating_acl_em

Updating way of getting entity manager to use base controller helper method
Merge branch '2.0' into 2.1

Conflicts:
	book/controller.rst
	book/forms.rst
	cookbook/map.rst.inc
[#1987] Changing getEntityManager to getManager
Merge pull request #1988 from richardmiller/cookbook_line_lengths

Reducing some example code line lengths
Merge pull request #1990 from johnkary/fixDeprecatedFormEvents

Remove reference to deprecated DataEvent and FilterDataEvent
Merge pull request #1992 from WouterJ/patch-17

Updated outdated Wikipedia link
Bugfixing a few typos; Adding install command for composer
Remove the reqire on app/autoload from code-example
Changing text which refers to the old autoloading mechanism

This only include minor changes.
Changing text which refers to the old app/autoload.php to mention "the Composer" way.
Removing wrong mentioning of a `src/autload.php`
Rewriting the autoload section to include composer
Reverting changes which remove mentioning of the app/autoload.php
Update components/http_foundation/introduction.rst

Typo in documentation that would cause an exception. setContent can not accept array. Assuming documentation meant setData.
Merge pull request #1997 from Cangit/patch-1

Update components/http_foundation/introduction.rst
Partially reverting some changes and improving the original content
Making a few changes to the existing description and adding docs for the Formatter Helper
Adding the formatterhelper.rst to index and map
Changing a few wordings as well as code references to methods
Fixing sysmte => system typo