* src/DisplayState.py: Rename from DbState, kepp only DisplayState
class.
* src/GrampsDbBase.py: Add DbState class.
* src/MapView.py: Swap zoom_in and zoom_out to reflect reality;
add place list with the ScrollableWindow, request size for the
place list.
* src/ViewManager.py: Use DisplayState.DisplayState.
* src/gramps_main.py: Use GrampsDbBase.DbState; add docstring;
svn: r5055