Version 1.1.0

• For json_encode() compatibility, all objects are encoded as JSON objects
  unless they implement Traversable and either return 0 as the first key or
  return no values at all.
• Testing for associative arrays is now more memory efficient and fails faster.
• JSON encoding errors now contain the error constant.
• The visibility for StreamJsonEncoder::write() and BufferJsonEncoder::write()
  has been changed to protected (as was originally intended).
• A new protected method AbstractJsonEncoder::getValueStack() has been added
  that returns the current unresolved value stack (for special write method
  implementations).
• An overridable protected method AbstractJsonEncoder::resolveValue() has
  been added which is used to resolve objects (i.e. resolving the value of
  closures and objects implementing JsonSerializable).