Remove -logtodebugger

`-logtodebugger` is a strange, obscure, WIN32-only (mostly MSVC) thing.
Let's clean up the options a bit get rid of it.

test_bitcoin was using fLogToDebugger as a way to prevent logging to
debug.log. For this, add a boolean (not exposed as option) fLogToDebugLog that
defaults to true and is disabled in the tests.

src/init.cpp

@@ -245,10 +245,6 @@ std::string HelpMessage(HelpMessageMode hmm)
     strUsage += "  -printtoconsole        " + _("Send trace/debug info to console instead of debug.log file") + "\n";
     strUsage += "  -regtest               " + _("Enter regression test mode, which uses a special chain in which blocks can be "
                                                 "solved instantly. This is intended for regression testing tools and app development.") + "\n";
-#ifdef WIN32
-    strUsage += "  -printtodebugger       " + _("Send trace/debug info to debugger") + "\n";
-#endif
-
     if (hmm == HMM_BITCOIN_QT)
     {
         strUsage += "  -server                " + _("Accept command line and JSON-RPC commands") + "\n";
@@ -492,7 +488,6 @@ bool AppInit2(boost::thread_group& threadGroup, bool fForceServer)
         fServer = GetBoolArg("-server", false);
 
     fPrintToConsole = GetBoolArg("-printtoconsole", false);
-    fPrintToDebugger = GetBoolArg("-printtodebugger", false);
     fLogTimestamps = GetBoolArg("-logtimestamps", true);
 #ifdef ENABLE_WALLET
     bool fDisableWallet = GetBoolArg("-disablewallet", false);