Serializer refactoring

[goetas]

currently implemented (currently the existing test suite has been fixed and is still green):

Ideas (to do? ):

• fix PSR
  • code style done
  • namespaces
• remove some features (move to a different repo)
  • PHPCR driver (is it used by somebody?)
  • Doctine driver (is it used by somebody? can it be enabled by default? does it work good enough)
  • Propel
  • PhpCollection and phpoption done
  • remove xml driver? (i love xml... but looks that im alone)
• visitors
  • make native types handled with listeners done (this creates 20-30 % of performance penality)
  • and make them treated in the same way as objects done
• use symfony property access to read properties
• allow to choose how to serialize arrays
  • as array
  • as object
  • skip if empty
• remove handle callback feature done
• graph navigator factory done
• splitted graph navigator into serialize navigator and unserialize navigator done
• converted type array into value object done

performance benchmark, this version is 20% slower 😢