Made ListNode abstract and items protected
Added ArrayNode
Renamed ListNode to CollectionNode to avoid confusion with list()
Added type to CollectionNode
Improved use trait parsing
Added ArrayLookupNode
Added missing break
Added VariableNode
Added VariableVariableNode
Added CompoundVariableNode
Added NamespacePathNode
Updated doc comment
Added node classes for try/catch/finally control structure
Added ReferenceVariableNode, eg. &
Added nodes for float, integer, string constants