fixed: added cookable prop to NicoAccount.
fixed: quit NicoCookable twice login when failed.
fixed: GetThumb,RankLoad's TaskProcessor stack stace output miss fixed.
e.getStackTrace() must be e.getStackTraceString().
fixed: bug-fixed: FileUtils.getSizeKb changed to .getSizeBytes. and added IFileSizeLimitChecker.
fixed: added some params to ExampleTaskParams for VideoDownTaskProcessor example.
added: NicoVideoDownTaskProcessor and its example.
fixed: changed ExampleTaskParams initialize way to avoid miss login.
moved-package: Task examples move to tasks/example package.