Use and propagate microsecond-precision timestamps to FormatTime

This enables sub-second precision timestamp formatting for logs and
clients without server-time.

modules/listsockets.cpp

@@ -154,8 +154,10 @@ class CListSockets : public CModule {
 
     CString GetCreatedTime(Csock* pSocket) {
         unsigned long long iStartTime = pSocket->GetStartTime();
-        time_t iTime = iStartTime / 1000;
-        return CUtils::FormatTime(iTime, "%Y-%m-%d %H:%M:%S",
+        timeval tv;
+        tv.tv_sec = iStartTime / 1000;
+        tv.tv_usec = iStartTime % 1000 * 1000;
+        return CUtils::FormatTime(tv, "%Y-%m-%d %H:%M:%S.%L",
                                   GetUser()->GetTimezone());
     }