Update DisplayPretty example to use ARC
! Replace SBJsonStreamParserAdapter with SBJsonChunkParser

Rather than having to configure a parser + adapter, you now just configure a
chunk parser; internally this will delegate to the stream parser.

The Chunk parser exposes a much more convenient block-based interface than the
clumsy callback one.

Add ErrorHandler block that returns errors found by the stream parser. This was
never supported in the Adapter.
Support stopping parsing after a certain number of partial documents
Minor comment fixes
Update NEWS + version numbers
Use the ChunkParser in the DisplayPretty example