Adding a section about the slice filter

This code example shows how to loop over a subset of values in order to implement one common use-case of "break" in PHP. I decided to use the "full" notation of slice rather than the sugared version (that example would just be "for user in users[:10]")
Adding link to slice filter per Stof's suggestion
minor typo in sort documentation
Fix filename for batch filter documentation
merged branch tommygnr/fix-docs-batch-filter (PR #1040)

This PR was merged into the master branch.

Discussion
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Fix filename for batch filter documentation

The documentation on the website for the batch filter currently 404s See: http://twig.sensiolabs.org/doc/filters/batch.html

I believe this is because the filename is incorrect. This PR fixes that.

Commits
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bb05942 Fix filename for batch filter documentation
merged branch ricardclau/typo_sort_doc (PR #1039)

This PR was merged into the master branch.

Discussion
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Minor typo in sort filter documentation

I've found this small typo while working on shuffle filter documentation in https://github.com/fabpot/Twig/pull/1038

I decided to create separate PR in case https://github.com/fabpot/Twig/pull/1038 got rejected

Best regards!

Commits
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1443b76 minor typo in sort documentation
merged branch beryllium/patch-1 (PR #1032)

This PR was merged into the master branch.

Discussion
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Adding a section about the slice filter to doc/tags/for.rst

This code example shows how to loop over a subset of values in order to implement one common use-case of "break" in PHP. I decided to use the "full" notation of slice rather than the sugared version (that example would just be "for user in users[:10]")

Commits
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202641a Adding link to slice filter per Stof's suggestion
8ebbaaa Adding a section about the slice filter
tweaked previous merge
Registration a Twig_SimpleFunction after extensions initialized throw not LogicException, but Fatal Error
merged branch ShadowPrince/master (PR #1042)

This PR was squashed before being merged into the master branch (closes #1042).

Discussion
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Registration a Twig_SimpleFunction after extensions initialized throw not LogicException, but Fatal Error

Registration a Twig_SimpleFunction after extensions initialized throw not LogicException, but Fatal Error:

$environment->addFunction(new Twig_SimpleFunction(...))
after 
$environment->render(...)
throws Fatal Error: 
object of Twig_SimpleFunction could not be converted to string

Commits
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92e97b9 Registration a Twig_SimpleFunction after extensions initialized throw not LogicException, but Fatal Error
updated CHANGELOG