Don't require server name in config file

The user might just want to load a bunch of settings and not
initiate a connection.
diff --git a/vncviewer/parameters.cxx b/vncviewer/parameters.cxx
index 16de6e3..51cce3d 100644
--- a/vncviewer/parameters.cxx
+++ b/vncviewer/parameters.cxx
@@ -540,6 +540,8 @@
   char decodingBuffer[buffersize];
   static char servername[sizeof(line)];
 
+  memset(servername, '\0', sizeof(servername));
+
   // Load from the registry or a predefined file if no filename was specified.
   if(filename == NULL) {