ve.copy: Remove obsolete copyArray and copyObject

These have been pointing to the same method for a while now,
we can safely remove these obsolete aliases and just use it
as generic copy.

* Each file touched by my editor had its new line at EOF fixed
  where absent
* Don't copy an otherwise unused empty object
  (ve.dm.Converter)
* Use common ve#copy syntax instead to create a link
  (ve.dm.Document, ve.dm.example)
* Remove redundant conditionals for isArray/copyArray/copyObject
  (ve.dm.example)

Change-Id: If560e658dc1fb59bf01f702c97e3e82a50a8a255