story #7511: Add list of accepted item types in BacklogItemRepresentation

Change-Id: Ic29026321527b6cb718d792ad5bf85a0bb726dab
story #7511: Drop into an item without child or collapsed (don't call REST routes)

Change-Id: Ifaff1942cbb309ac27a75bd1cf8a95adc10b92c2
story #7511: When an item is dropped, REST routes are called

Change-Id: I00ba000ae4be697ff0559838f07f7b9bef164144
story #7511: Submilestone initial effort is updated when its content is updated

Change-Id: I84eb20057c7798bc15dffef1477b056b09a6ef0d
story #7511: submilestones links work

Change-Id: Ib5346715343f5868a9a57044db0994ff65b538ab
Merge commit 'refs/changes/40/3340/3' of ssh://gerrit.tuleap.net:29418/tuleap into HEAD

* ssh://gerrit.tuleap.net:29418/tuleap:
  story #7511: submilestones links work
  story #7511: Submilestone initial effort is updated when its content is updated
  story #7511: When an item is dropped, REST routes are called
  story #7511: Drop into an item without child or collapsed (don't call REST routes)
  story #7511: Add list of accepted item types in BacklogItemRepresentation

Change-Id: Ibabdd1cb5d657e35ca66bc066bd6ee0a63611d6b
This is Tuleap 7.7.99.67

Change-Id: I5feba6985325009165af093bc77f266dc1b771f9