Added HasChildren() to composite and performance improvement when view elements has no children
Added AncestorChanged() mechanism
Added AncestorChanged to scaler
Some further performance improvment for view elements with no children
Initial implementation of Eclipse like anchors and connections - about to be redesigned.

To have anchors as child elements rather than linked elements.
Anchors are no structural view elements.
Anchors are now structural view elments (delete commit)
Validate now split into ValidateUp (ancestors) and ValidateDown (descendents).
Box Anchor now chops the box.