[DEP] Deprecate Differencer transformer

[TonyBagnall]

Fixes #700 resolves #1534

Deprecate broken Differencer class

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[MatthewMiddlehurst]

Agree the implementation is overly complex for what it is, but I can see the use in a differencer transform. Should be a nice good first issue to do it in the new interface?

[TonyBagnall]

Agree the implementation is overly complex for what it is, but I can see the use in a differencer transform. Should be a nice good first issue to do it in the new interface?

yes for sure, good idea, particularly a working inverse