Commits
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d8b0d797 Added the LocaleListener to handle setting the locale

Discussion
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Added the LocaleListener to handle setting the locale

This registers the LocaleListener setting the request locale according to the matching of the special ``_locale`` parameter and setting the locale in the routing RequestContext so that it is always available.

This PR should be merged only after the update of the subtree split as it requires the typehint change merged just before in Symfony