Update R4.0.5 — Source of the Nile Digital Edition Steam update #1096354

* Improved the mouse-over behaviour of the activity buttons. * Slightly reduced the volume of the native drums in the policy screen. * Made minor alterations to the tribal zones of Fulani, Pygmy and Xhosa natives to better reflect the ethnogeography of the time. * Bushmen have been placed within their correct tribal zone.