Single file downloader
Description: Thunder can not download to download resources, single-threaded operating
input: a http text, requires that each link is unique and the file name can not be repeated, if repeated, then, after downloading the file will be overwritten
Note: requirements to ensure adequate exception handling to ensure the cmd command window not quit
matters process: file stream open the text, circulating read each line inside, get Download, get the file name, and get to save the absolute path of the file, start the download
extended: record failed download link, and add speed tips
