Added UTs for is retry allowed. All possible states are now considered.
Removed separate submission handler for closing and filling orders. Most
of the logic is now directly in OrderMessageState; this design is
cleaner and leads to simpler implementations. Logging for different
types of submission is done via an interface.
OrderStateUtils class is no longer needed. All functionality has been
moven to OrderUtils and OrderMessageState.
Method renamings on orderMessageState class. Fixed bug in handling of
waiting retry loop: loop would exit when message indicates a reject.