Fix minor bugs

+ Fix compiler error under Windows which occurs under Unity's MonoDevelop with default project setup.
  The error has to do with the default parametrization of methods. MonoDevelop recognizes
  default parametrization as error under Windows if the target .NET Framework is below version 4.0.

+ Remove the overloaded operators == and != which should use the >> contents << of a class to fulfill their
  functionality and not the reference of instantiated objects. Furthermore, the overloading of the operators ==
  and != leads to a warning if the methods Equals and GetHashCode are not implemented. These warnings
  get resolved through removing the operators which are not really needed anyway.

+ Resolve some minor warnings of unused but allocated variables and a warning due to a missing method override.
Make SimpleBSON compatible to Windows Phone 8