This allows us to put other internal data in there in the future. Also
passing it through the Node constructor properly now.
* ve.dm.Node
** Rename fringeWhitespace property to internal
** Add internal parameter to constructor
** Remove setFringeWhitespace()
* Increase the number of parameters passed through by ve.Factory to 3
* Pass through .internal from linmod to nodeFactory in ve.dm.Document
* ve.dm.Converter
** Rename .fringeWhitespace to .internal.whitespace and make it an array
** Store a temporary reference to .internal in domElement.veInternal
* Add internal to all node constructors except TextNode
Tests:
* Update for fringeWhitespace->internal rename
* Add third parameter to ve.Factory tests
* Add .internal to getNodeTreeSummary
Change-Id: If20c0bb78fee3efa55f72e51e7fc261283358de7
