Refactored MarkRoundingDecoder - it now implements MessageDecoder.
Tidied up MarkRounding - it is now documented and has getters. Also Created MarkRoundingBoatStatusEnum, MarkRoundingIDEnum, MarkRoundingSideEnum, MarkRoundingTypeEnum.
Added MarkRoundingDecoderTest.
issue #35#36
#story[1095]