Merge branch '3.4' into 4.3

* 3.4:
  Add @a2lix/symfony-collection solution

Author: javiereguiluz

form/form_collections.rst

@@ -709,13 +709,14 @@ the relationship between the removed ``Tag`` and ``Task`` object.
     updated (whether you're adding new tags or removing existing tags) on
     each Tag object itself.
 
-.. sidebar:: Form collection jQuery plugin
+.. seealso::
 
-    The jQuery plugin  `symfony-collection`_ helps with ``collection`` form elements,
-    by providing the JavaScript functionality needed to add, edit and delete
-    elements of the collection. More advanced functionality like moving or duplicating
-    an element in the collection and customizing the buttons is also possible.
+    The Symfony community has created some JavaScript packages that provide the
+    functionality needed to add, edit and delete elements of the collection.
+    Check out the `@a2lix/symfony-collection`_ package for modern browsers and
+    the `symfony-collection`_ package based on jQuery for the rest of browsers.
 
 .. _`Owning Side and Inverse Side`: https://www.doctrine-project.org/projects/doctrine-orm/en/current/reference/unitofwork-associations.html
 .. _`JSFiddle`: http://jsfiddle.net/847Kf/4/
+.. _`@a2lix/symfony-collection`: https://github.com/a2lix/symfony-collection
 .. _`symfony-collection`: https://github.com/ninsuo/symfony-collection