Refactor consensus for simulation (RIPD-1011):

This is a substantial refactor of the consensus code and also introduces
a basic consensus simulation and testing framework.  The new generic/templated
version is in src/ripple/consensus and documents the current type requirements.
The version adapted for the RCL is in src/ripple/app/consensus.  The testing
framework is in src/test/csf.

Minor behavioral changes/fixes include:
* Adjust close time offset even when not validating.
* Remove spurious proposing_ = false call at end of handleLCL.
* Remove unused functionality provided by checkLastValidation.
* Separate open and converge time
* Don't send a bow out if we're not proposing
* Prevent consensus stopping if NetworkOPs switches to disconnect mode while
  consensus accepts a ledger
* Prevent a corner case in which Consensus::gotTxSet or Consensus::peerProposal
  has the potential to update internal state while an dispatched accept job is
  running.
* Distinguish external and internal calls to startNewRound.  Only external
  calls can reset the proposing_ state of consensus

src/test/unity/consensus_test_unity.cpp

@@ -0,0 +1,21 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of rippled: https://github.com/ripple/rippled
+    Copyright (c) 2012-2016 Ripple Labs Inc.
+
+    Permission to use, copy, modify, and/or distribute this software for any
+    purpose  with  or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#include <test/consensus/Consensus_test.cpp>
+#include <test/consensus/LedgerTiming_test.cpp>

src/test/unity/csf_unity.cpp

@@ -0,0 +1,23 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of rippled: https://github.com/ripple/rippled
+    Copyright (c) 2012-2017 Ripple Labs Inc.
+
+    Permission to use, copy, modify, and/or distribute this software for any
+    purpose  with  or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#include <BeastConfig.h>
+
+#include <test/csf/BasicNetwork_test.cpp>
+#include <test/csf/impl/UNL.cpp>

src/test/unity/jtx_unity.cpp

@@ -49,7 +49,5 @@
 #include <test/jtx/impl/JSONRPCClient.cpp>
 #include <test/jtx/impl/ManualTimeKeeper.cpp>
 #include <test/jtx/impl/WSClient.cpp>
-
-#include <test/jtx/BasicNetwork_test.cpp>
 #include <test/jtx/Env_test.cpp>
 #include <test/jtx/WSClient_test.cpp>