Node method cleanups

For methods which exist in dm & ce, move to ve.Node as abstract
and replace documentation in dm & ce with inheritdoc.

For methods which only access other methods available in ve.Node,
move to ve.Node (e.g. getRange).

Give getRange the same signature as getOuterRange.

Change-Id: I49ab9b76f503ff3e7355713d6551cb27476cfdde
Add isAllowed(Child|Parent)NodeType to ve.Node

Change-Id: If0a08cc0b5af5161bf3417537bb320cfb20f8e41
Merge "Node method cleanups"
Merge "Add isAllowed(Child|Parent)NodeType to ve.Node"