Massive cleanup of flow user scripts into callback_definitions

scripts/lua/modules/callback_definitions/flow/zero_tcp_window.lua

@@ -0,0 +1,35 @@
+--
+-- (C) 2020 - ntop.org
+--
+
+local alerts_api = require("alerts_api")
+local alert_severities = require "alert_severities"
+local user_scripts = require("user_scripts")
+local alert_consts = require("alert_consts")
+local flow_alert_keys = require "flow_alert_keys"
+
+-- #################################################################
+
+local script = {
+  -- Script category
+  category = user_scripts.script_categories.network,
+
+  -- NB atm working only for packet interfaces
+  packet_interface_only = true,
+
+  -- This script is only for alerts generation
+  alert_id = flow_alert_keys.flow_alert_zero_tcp_window,
+
+  default_value = {
+   severity = alert_severities.warning,
+  },
+  
+  gui = {
+    i18n_title        = "flow_callbacks.zero_tcp_window_title",
+    i18n_description  = "flow_callbacks.zero_tcp_window_description",
+  }
+}
+
+-- #################################################################
+
+return script