message: Added Concurrency flag to enable/disable the liveness problem.
diff: @@ -21,7 +21,8 @@ EXTENDS Naturals, FiniteSets, Sequences
  CONSTANT MaxHeight, \* Maximum height of any chain in the system.
  - MaxBufLen \* Length (size) of message buffers.
  + MaxBufLen, \* Length (size) of message buffers.
  + Concurrency \* Flag for enabling concurrent relayers.
  ASSUME MaxHeight > 1
  @@ -222,7 +223,7 @@ RelayNextEnv ==
  *)
  NextEnv ==
  - \/ DefaultNextEnv
  + \/ Concurrency /\ DefaultNextEnv
  \/ RelayNextEnv
  @@ -328,7 +329,7 @@ Consistency ==
  =============================================================================
  \* Modification History
  -\* Last modified Mon Jun 22 16:53:20 CEST 2020 by adi
  +\* Last modified Tue Jun 23 10:57:28 CEST 2020 by adi
  \* Created Fri Apr 24 18:51:07 CEST 2020 by adi
  