Separate basic and all statistics display
Add custom DRb protocol loader

This allows deeper analysis of DRb protocol messages

Collect statistics from the message rather than being informed
indirectly.
Test message and result processing
Track and display statistics for message sends

When exiting, drbdump now displays statistics for message sends
including message sent, arguments for the message, count sent, average
number of allocations and standard deviation of message sends.
Add marshal-structure dependency
Enable travis testing