prefer focus-window over input-focus. More consistent.
add focus-window
tiling policy
Fix rwind not starting

Problem was workspaces were not fully initialized after adding a check.
fix window not retrieved in workspaces
windows are added to the X save set, to avoid being lost if the WM dies
relayout on map request, unmap and destroy
fix only viewable windows must be used in the layout
- can-kill-window? -> window-user-killable? for consistency with window-user-movable and window-user-resizable in keymap.
- add on-init-workspace in policies to be able to re-layout
fix init workspaces in policy%
focus is remembered when switching workspaces
window border on focus window.