autoStart property in DataExtractors

[haxdai]

DataExtractors start at platform initialization (eng.initPlatform(session)). It would be useful to prevent this behavior when extractors are meant to be executed on demand. Maybe using a property with default value to true:

eng.dataExtractors["UserExtractor"] = {
  autoStart: false,
  timer: { time: 10, unit: "m" },
  dataSource: "User",
  class: "my.package.UserExtractor"
};