npe in xmla with empty set rows axis

NPE from null hierarchy in
mondrian.xmla.XmlaHandler$MDDataSet_Multidimensional.writeHierarchyInfo
expose MEMBER_KEY property for xmla/adomd.net
expression property and member_ordinal bug workaround

+ EXPRESSION xmla member property
transient workaround for ocasional bug causing persistent -1
member_ordinal
more properties to avoid exceptions on adomd client

not complete
+XmlaUseMSSASError property, make exceptions parseable by adomd.net
tentative HierarchyOrigin, change numeric precision and scale defaults
default LastDataUpdate to LastSchemaUpdate

avoid exception on adomdclient CubeDef.LastUpdated
Merge pull request #1 from tgf/evergreen

Evergreen