Add support for optional 'SameSite' cookie attribute

As described in the definition document by the ietf:
https://tools.ietf.org/html/draft-west-first-party-cookies-07

"The 'SameSite' attribute allows servers to assert that a cookie
ought not to be sent along with cross-site requests. This assertion
allows user agents to mitigate the risk of cross-origin information
leakage, and provides some protection against cross-site request
forgery attacks."

Revert "Optimize 'OFS.ObjectManager.__contains__' method"

It causes problems with ZCatalog indexes.
See https://github.com/zopefoundation/Zope/issues/69

This reverts commit 753683e3.

Quote variables in manage_tabs and manage_container to avoid XSS [2.13]

From Products.PloneHotfix20160830.

The 3.0 release of the project contains no code. It allows projects
to declare a dependency on it for forward compatibility with Zope 4.

Apply hotfix 20160419 rebased

From Products.PloneHotfix20160419.

Optimize "OFS.ObjectManager.__contains__" method (backport)

Backported from master.

fix ReST rendering problem in changelog

[ci skip]

[ci skip]

[ci skip]

Conflicts:
	doc/CHANGES.rst

The ``fivetest.mo`` files are required by i18n tests.

This reverts commit a059efe1.

[ci skip]

You can use zest.pocompile (in combination with zest.releaser)
to generate and include .mo files.

Don't bail on WindowsError which is not existing on non-windows systems.

Discussion see https://github.com/zopefoundation/Zope/commit/87c5992e7e40604df206bb713e42bafd5919fe64