adding rexpro meta container and field definition classes
adding static define method to meta field
adding Meta field to RexProMessage
adding Meta field definitions, and getters and setters for the script and session request messages
changing field definitions to getter
refactoring filters to work with meta field
refactoring various classes to work with rexpro meta field
adding rexpromessage meta class and special msgpack template to allow it to serialize/deserialize Object values
updating message creation to work with updated message meta setup