[MONDRIAN-1995] backport of hanger dimension functionality from Mondrian
4.0.  Due to the complexity of cube initialization, we couldn't do a full
backport.  Hanger dimensions must have either a dummy dimension table to
define a default member, or include an all member.
Updated trace to make it easier to link to other log lines.
[MONDRIAN-1995] fixed issue with hanger dims that specify dummy dim table.