Add "checkpoints" option, to permit disabling of checkpoint logic.

src/checkpoints.cpp

@@ -39,6 +39,9 @@ namespace Checkpoints
 
     bool CheckBlock(int nHeight, const uint256& hash)
     {
+        if (!GetBoolArg("-checkpoints", false))
+            return true;
+
         MapCheckpoints& checkpoints = (fTestNet ? mapCheckpointsTestnet : mapCheckpoints);
 
         MapCheckpoints::const_iterator i = checkpoints.find(nHeight);
@@ -48,6 +51,9 @@ namespace Checkpoints
 
     int GetTotalBlocksEstimate()
     {
+        if (!GetBoolArg("-checkpoints", false))
+            return 0;
+
         MapCheckpoints& checkpoints = (fTestNet ? mapCheckpointsTestnet : mapCheckpoints);
 
         return checkpoints.rbegin()->first;
@@ -55,6 +61,9 @@ namespace Checkpoints
 
     CBlockIndex* GetLastCheckpoint(const std::map<uint256, CBlockIndex*>& mapBlockIndex)
     {
+        if (!GetBoolArg("-checkpoints", false))
+            return NULL;
+
         MapCheckpoints& checkpoints = (fTestNet ? mapCheckpointsTestnet : mapCheckpoints);
 
         BOOST_REVERSE_FOREACH(const MapCheckpoints::value_type& i, checkpoints)

src/init.cpp

@@ -258,6 +258,7 @@ std::string HelpMessage()
         "  -onlynet=<net>         " + _("Only connect to nodes in network <net> (IPv4, IPv6 or Tor)") + "\n" +
         "  -discover              " + _("Discover own IP address (default: 1 when listening and no -externalip)") + "\n" +
         "  -irc                   " + _("Find peers using internet relay chat (default: 0)") + "\n" +
+        "  -checkpoints           " + _("Lock in block chain with compiled-in checkpoints (default: 1)") + "\n" +
         "  -listen                " + _("Accept connections from outside (default: 1 if no -proxy or -connect)") + "\n" +
         "  -bind=<addr>           " + _("Bind to given address and always listen on it. Use [host]:port notation for IPv6") + "\n" +
         "  -dnsseed               " + _("Find peers using DNS lookup (default: 1 unless -connect)") + "\n" +