WaveformZoom controller becomes more like other part of the app.

Removed some Java-ism (but not all).
Sanitize some inter-control relationship on WaveformZoom.

It should be instantiated from FormMain.xml in the end. So far sanitize
part of it.
Now WaveformZoom(Impl) does not require constructor parameters.

And hence it is XML-ready.
suppress some warnings (XML doc comments, I don't care about Japanese comment).