Fix undefined player color errorspam in Atlas after placing an entity, changing the civ and starting the simulation following rP19965 / D623, refs #4643.

The commit had removed the fallback color as there is no traceable use case.
Copy the Player color from the old to the new player entity in ReplacePlayer before the ownership changes occur, so that it is always initialized before read.

Refs rP16092
Reported By: temple