! 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
Update README.md
Update SBJsonChunkParser.h
Improve links in NEWS
Rename type
Make SBJsonChunkParser "immutable" by removing properties
Move max-depth error handling from stream parser to chunk-parser
Remove parser as argument to all its delegate methods
Doc fixes
Remove unnused code
Changed secondary init method to be a class method instead
Improved method name for "partial" documents
Remove old SBJsonParser and rename SBJsonChunkParser to SBJsonParser

- Updated tests to suit.
- Rename item "return" block.
- Rename the main constructor / initialiser. (Again.)
- Add two more constructor methods for the parser.
Add a bit of documentation to the blocks
Rename classes, constants & enums to add major version number (4)

This is to allow SBJson4 to be used alongside previous versions of itself. This
can be useful now that SBJson is embedded by so many popular libraries.
Additionally, if you're already using it you may not want to replace all usages
in one go; this way you don't have to.
Add documentation for more convenience constructors

Also rename arguments in initialiser to be in line with constructors.