7195: vinv revisit

modify VisualLayoutArgs
7196: rename VisualElementArgs

to LayoutPhaseVisitor
7197: rename dbugRootElement

to RootGraphic
7200: remove vinv

not complete!
7202: remove GetVinv
7204: remove vinv
7206: VisualLayer owners
Merge branch 'v_vinv' into v1.7