C++: Introduce RunCondition to Run Metadata

This MR changes/improves data transmission in a variety of situations:

• It adds a interrupting_transmitter method which sends an EOR if the previous state was RUN. This closes #142 (closed).
• Receivers now also generate a substitute EOR when no EOR is received in stopping, there is no reason this should not be the same as in interrupting..
• Receivers now keep track of missed messages per-transmitter, not only globally.
• There is a new code ("condition") added to the metadata of the run indicating the condition of the data. The following values are added as text and code:
  • GOOD (1): The run has concluded normally, no other information has been provided by the sender
  • TAINTED (2): The run has concluded normally, but the data has been marked as tainted by the sender
  • INCOMPLETE (3): The run has concluded normally, but the receiver has noticed missing messages in the sequence
  • INTERRUPTED (4): The run has been interrupted by this sender because of a failure condition elsewhere in the Constellation
  • ABORTED (5): The run has been aborted by the sender and the EOR message has been appended by the receiver
• Transmitter have the possibility to mark a run as TAINTED - the idea here is that the code noticed something being odd and can tag the run.
• Receiver sets the INCOMPLETE condition tag to the run metadata (overwriting anything from the transmitter) if there are missing sequences recorded for that connection.
• Tests for data transmission in tainted-run, transmitter-interrupted and transmitter-failed runs are added
• Documents data concepts