fix: Consolidate message traits

Signed-off-by: Jussi Virtanen <jussi.virtanen@valotrading.com>
fix: Remove RequestMessage interface

Signed-off-by: Jussi Virtanen <jussi.virtanen@valotrading.com>
fix: Rename UserDefinedMessage to TradeCancelCorrect

Signed-off-by: Jussi Virtanen <jussi.virtanen@valotrading.com>
fix: Convert NewOrderSingle to Scala

Signed-off-by: Jussi Virtanen <jussi.virtanen@valotrading.com>
fix: Convert OrderCancelRequest to Scala

Signed-off-by: Jussi Virtanen <jussi.virtanen@valotrading.com>
fix: Reformat message traits

Signed-off-by: Jussi Virtanen <jussi.virtanen@valotrading.com>
Merge pull request #153 from jvirtanen/cleanups/fix-message-trait

Clean up FIX message traits