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/test/test_bitcoin.cpp

@@ -26,7 +26,7 @@ struct TestingSetup {
     boost::thread_group threadGroup;
 
     TestingSetup() {
-        fPrintToDebugger = true; // don't want to write to debug.log file
+        fPrintToDebugLog = false; // don't want to write to debug.log file
         noui_connect();
 #ifdef ENABLE_WALLET
         bitdb.MakeMock();