Finished to implement -[ETFreeLayout didLoadObjectGraph] correctly

Fixed typo in property name ETMoveTool.shouldProduceTranslateActions
Wrote TestColumnLayoutPersistency.

Declared some missing persistent properties in ETComputedLayout model description

Added missing calls to -will/DidChangeForProperty: in ETComputedLayout

Added missing calls to -renderAndInvalidateDisplay in ETPositional/ComputedLayout

Don't skip the resizing in -[ETPositionalLayout resizeItems:toScaleFactor:] for ETSizeConstraintStyleNone

Fixed typo in ETComputedLayout.horizontalAlignment property name

Fixed missing separator identifiers in ETLayoutItemFactory