Merge pull request #478 from cdavis5e/log-to-stderr

Log to stderr instead of stdout.
diff --git a/Common/MVKLogging.h b/Common/MVKLogging.h
index c7af750..0975ccd 100644
--- a/Common/MVKLogging.h
+++ b/Common/MVKLogging.h
@@ -183,7 +183,7 @@
 	char lvlFmt[strlen(lvlStr) + strlen(format) + 5];
 	sprintf(lvlFmt, "[%s] %s\n", lvlStr, format);
 
-	if (logToPrintf) { vprintf(lvlFmt, args); }
+	if (logToPrintf) { vfprintf(stderr, lvlFmt, args); }
 //	if (logToASL) { asl_vlog(NULL, NULL, aslLvl, lvlFmt, args); }       // Multi-threaded ASL support requires a separate ASL client to be opened per thread!
 }