• For JSON_TYPE_INT and JSON_TYPE_FLOAT allow to encode numeric values
  above 2^64 in PV slot via Math::BigInt/Float (#145, #148, #149 by Pali)
  
• For JSON_TYPE_INT and JSON_TYPE_FLOAT encoder allow to pass Math::BigInt
  and Math::BigFloat objects with allow_bignum. (#147 by Pali)
  
• Fix encoding floating point values above 2^64 in PV slot to JSON_TYPE_INT
  (#148, #150 by Pali)
  
• Do not allow serializing objects when convert_blessed is not enabled.
  (#146 by Pali)