--kill-blockchain option in eth.

Fixes #1367

eth/main.cpp

@@ -119,6 +119,7 @@ void help()
 		<< "	-j,--json-rpc  Enable JSON-RPC server (default: off)." << endl
 		<< "	--json-rpc-port	 Specify JSON-RPC server port (implies '-j', default: 8080)." << endl
 #endif
+		<< "    -K,--kill-blockchain  First kill the blockchain." << endl
 		<< "    -l,--listen <port>  Listen on the given port for incoming connected (default: 30303)." << endl
 		<< "    -L,--local-networking Use peers whose addresses are local." << endl
 		<< "    -m,--mining <on/off/number>  Enable mining, optionally for a specified number of blocks (Default: off)" << endl
@@ -214,6 +215,7 @@ int main(int argc, char** argv)
 	bool upnp = true;
 	bool useLocal = false;
 	bool forceMining = false;
+	bool killChain = false;
 	bool jit = false;
 	bool structuredLogging = false;
 	string structuredLoggingFormat = "%Y-%m-%dT%H:%M:%S";
@@ -270,6 +272,8 @@ int main(int argc, char** argv)
 		}
 		else if (arg == "-L" || arg == "--local-networking")
 			useLocal = true;
+		else if (arg == "-K" || arg == "--kill-blockchain")
+			killChain = true;
 		else if ((arg == "-c" || arg == "--client-name") && i + 1 < argc)
 			clientName = argv[++i];
 		else if ((arg == "-a" || arg == "--address" || arg == "--coinbase-address") && i + 1 < argc)
@@ -419,7 +423,7 @@ int main(int argc, char** argv)
 	dev::WebThreeDirect web3(
 		clientImplString,
 		dbPath,
-		false,
+		killChain,
 		mode == NodeMode::Full ? set<string>{"eth", "shh"} : set<string>(),
 		netPrefs,
 		&nodesState,