Rename CreateEntity and CreateItem to NewEntity and NewItem

This change makes the naming of the specal pages Special:CreateItem
and Special:NewProperty consistent as the create item page will be
Special:NewItem. There are also aliases to make Special:CreateItem
and Special:CreateProperty work.

This changeset has some consequences in messages, but unfortunatly
a lot of them has also changed keys.

Patchset 6: Rebased
Patchset 10: Rebased
Patchset 11: cleanup
Patchset 12: cleanup

Change-Id: Ic2d7c49f09f7222249b47dd3d946321d8e3302d3
Merge "Rename CreateEntity and CreateItem to NewEntity and NewItem"