New rules for layoutopt: IncorrectHeight/WidthIn[Horizontal]ScrollView, UselessView.

This change also refactors the uix library to remove an unnecessary class (LayoutNode.)
The refactoring helps writing cleaner script by accessing only the node object instead
of xml and node. This change also augment the capabilities of the node in Groovy scripts.

Change-Id: Id7515f9a79826909834d82496a6d9dfbc19988ad