removed hidden properties ghost logo.
fixed a bug in ElementHelper around hidden.
removed hiddens from PropertyType and simplified PropertiesStep.
got rid of Element.value(key,orElse) to limit the number of methods for the sake of @spmallette Strategy work.
minor nothing TODO note.
Renamed GraphStrategy implementations to be less verbose.
minor doc tweak
updated CHANGELOG about hidden properties removed.
lots of simplification on StrategyWrappedXXX. No more StreamFactory for one :). HadoopGraph now has StructureStandardSuite run against it fine. Fixed up VariablesTest as it was lacking some feature checking. The toString() of a StrategyWrappedXXX is v[1]*.
Rename DefaultGraphStrategy to IdentityStrategy.
Moved IdentityStrategy to it's own class.
Renamed the StrategyWrapped prefix to just Strategy.

For example StrategyWrappedGraph is now just StrategyGraph.
Remove hiddens GraphStrategy methods. #403
Remove more references to hidden in docs/comments.
Remove reference to hidden in comments.
fixed code samples in intro section
fixed code samples in The Graph section
added Groovy example for SubgraphStrategy
Changed reference from DefaultGraphStrategy to IdentityGraphStrategy.
Merge branch 'master' into check-docs