Accept replacebyfee=opt-in for turning on opt-in RBF

Basic forward-compatibility with more flexible parameters like fss

src/init.cpp

@@ -47,8 +47,10 @@
 #include <signal.h>
 #endif
 
+#include <boost/algorithm/string/classification.hpp>
 #include <boost/algorithm/string/predicate.hpp>
 #include <boost/algorithm/string/replace.hpp>
+#include <boost/algorithm/string/split.hpp>
 #include <boost/bind.hpp>
 #include <boost/filesystem.hpp>
 #include <boost/function.hpp>
@@ -1030,7 +1032,20 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
         nLocalServices |= NODE_BLOOM;
 
     nMaxTipAge = GetArg("-maxtipage", DEFAULT_MAX_TIP_AGE);
+
     fEnableReplacement = GetBoolArg("-replacebyfee", DEFAULT_ENABLE_REPLACEMENT);
+    if ((!fEnableReplacement) && mapArgs.count("-replacebyfee")) {
+        // Minimal effort at forwards compatibility
+        std::string strReplacementModeList = GetArg("-replacebyfee", "");  // default is impossible
+        std::vector<std::string> vstrReplacementModes;
+        boost::split(vstrReplacementModes, strReplacementModeList, boost::is_any_of(","));
+        BOOST_FOREACH(const std::string& strReplacementMode, vstrReplacementModes) {
+            if (strReplacementMode == "opt-in") {
+                fEnableReplacement = true;
+                break;
+            }
+        }
+    }
 
     // ********************************************************* Step 4: application initialization: dir lock, daemonize, pidfile, debug log