Add config option to supress focus requests across workspaces
In commit
d6c134f420bfa1cd6b6a9474d01548933b559901 ("Do not switch
workspace to follow new windows in others") the default behavior
was changed, and workspace switching to follow focus requests was
strictly forbidden.
Although that seems to be a sane thing to do by default, that raises
concerns about whether Window Maker could be more flexible in that
respect -- allowing the user to choose which applications are or
are not allowed to do that.
This patch adds such configuration, located in the "Advanced Options"
submenu of the top-level "Attributes" menu.