[tei-council] measured and measurement

[Lou Burnard]

The MS module defines an attribute class "measured" which adds 
attributes "unit" and "scope" to a number of elements.

The ST module defines an attribute class "measurement" which adds 
attributes "unit" "quantity" and "commodity"

There is evidentluy some overlap here, but I'm not sure how best to 
resolve it.

Constructive suggestions would be welcomed.