Backport MGNLUI-3862 to the 5.4 release branch; original description after the break.

Reordering fields doesn't work with delegating transformer implementations for the MultiValue field.

The MultiField component only implements the reordering itself, instead of delegating it to a common API for all multivalue transformers.

In worst case, if this cannot be done, then the reordering arrows should be hidden at least.

Updated in 2016-12-15
The final fix hides the up/down buttons if transfomerClass is DelegatingMultiValueFieldTransformer or its subclasses.