Removed main.h dependency from rpcserver.cpp

Rebased by @laanwj:

- update for RPC methods added since 84d13ee: setmocktime,
  invalidateblock, reconsiderblock. Only the first, setmocktime, required a change,
  the other two are thread safe.

src/init.cpp

@@ -234,6 +234,26 @@ bool static Bind(const CService &addr, unsigned int flags) {
     return true;
 }
 
+void OnRPCStopped()
+{
+    cvBlockChange.notify_all();
+    LogPrint("rpc", "RPC stopped.\n");
+}
+
+void OnRPCPreCommand(const CRPCCommand& cmd)
+{
+#ifdef ENABLE_WALLET
+    if (cmd.reqWallet && !pwalletMain)
+        throw JSONRPCError(RPC_METHOD_NOT_FOUND, "Method not found (disabled)");
+#endif
+
+    // Observe safe mode
+    string strWarning = GetWarnings("rpc");
+    if (strWarning != "" && !GetBoolArg("-disablesafemode", false) &&
+        !cmd.okSafeMode)
+        throw JSONRPCError(RPC_FORBIDDEN_BY_SAFE_MODE, string("Safe mode: ") + strWarning);
+}
+
 std::string HelpMessage(HelpMessageMode mode)
 {
     // When adding new options to the categories, please keep and ensure alphabetical ordering.
@@ -802,6 +822,8 @@ bool AppInit2(boost::thread_group& threadGroup)
     if (fServer)
     {
         uiInterface.InitMessage.connect(SetRPCWarmupStatus);
+        RPCServer::OnStopped(&OnRPCStopped);
+        RPCServer::OnPreCommand(&OnRPCPreCommand);
         StartRPCThreads();
     }