Allow top planning to sprint planning without interruption

Add the link to the panes in each submilestone in the planning pane.

This allow to do sprint planning and to access to a specific sprint
without having to come back to the agiledashboard or worse to click on
the awfully slow backlog/planning pane.

Change-Id: I9b11f51de74e2f7d6a578fab48304bca50324aef
Do not display the link to the legacy pane in new panes

I would like to prevent users to inadvertently switch to nice user
experience (latest planning and content panes) to awfull time load with
the legacy backlog/planning pane.

Change-Id: If73525ad9e47f8d05bf4ab0c21f38f22d8a59653
New panes are not anymore in lab mode

Change-Id: I2a5b39d1be5ae8d4caad260c2d977e268f903619
Legacy Backlog/Planning view will be removed in Tuleap 6.4

Change-Id: Ib6eb86c6c38c2e39e92a546b3ff3ec762f848cd9
Include the top milestone in the breadcrumbs

Change-Id: I2ebded558af8f7fe5d639bd4c3f2b3ab502d16bc
Merge remote-tracking branch 'gerrit/4044_browse_from_milestone_to_another' into HEAD

* bender/4044_browse_from_milestone_to_another:
  Include the top milestone in the breadcrumbs
  Legacy Backlog/Planning view will be removed in Tuleap 6.4
  New panes are not anymore in lab mode
  Do not display the link to the legacy pane in new panes
  Allow top planning to sprint planning without interruption

Change-Id: I1c63b71b5efc86d2e1a97926fc30cd761ee3bbad
This is Tuleap 6.2.99.28

Change-Id: I0cae34f52dfef5b94593c3ba722739c9c961398e