Added creation and periodic update of a file called "status" in the home directory that contains peer link status. Useful for debugging and statistics. Send it SIGHUP to force an update now. Otherwise it updates every 120 seconds.

node/Constants.hpp

@@ -253,6 +253,11 @@ error_no_ZT_ARCH
  */
 #define ZT_AUTOCONFIGURE_CHECK_DELAY 15000
 
+/**
+ * Delay between updates of status file in home directory
+ */
+#define ZT_STATUS_OUTPUT_PERIOD 120000
+
 /**
  * Minimum delay in Node service loop
  *