[BlockVector]
add header ftraits.hh as we are using the FieldTraits now
[BCRSMatrix]
use FieldTraits to determin the return type of the norm methods
[Matrix]
use FieldTraits to determin the return type of the norm methods
[test]
update matrixtest to use the FieldTraits and not assume double as the return value of *_norm
[ScaledIDMatrix]
use FieldTraits to determin the return type of the norm methods
[MultiTypeBlockVector]
use FieldTraits to determin the return type of the norm methods