This PR contains several internal and public API changes which include:

• Reflection is no longer used for reading/writing, instead, each class has its own Read/Write method defined manually
• Classes no longer have custom constructors, instead, they implement the ISerializable interface which makes the Read and Write methods available
• When serializing a format, a single SBinaryWriter instance is used and all subclasses write their data through it, this avoid all the memory allocations which were a consequence of the multiple GetBytes method invocations
• The static Reader class was renamed to ParsecReader, and its methods were renamed from ReadFromXXXX to FromXXXX, i.e. Parsec.ReadFromFile -> ParsecReader.FromFile
• The ItemDefinitionEp5 and ItemDefinitionEp6 classes were merged into a single ItemDefinition class
• Files can now be read with a specific encoding by passing it to the FromXX method

Overall, the public API hasn't changed much, but the internal changes resulted in reducing memory allocations and improved the performance considerably.