Adding resume support

[knassar702]

Suppose someone runs Lotus on large targets, such as 10,000 URLs, and some scripts fail, or the user decides to stop Lotus and modify the script when the progress of Lotus was at 6,000 URLs. Instead of rerunning Lotus on the 6,000 already scanned URLs, the user can pass a resume.cfg file that contains the index where Lotus stopped at the last task. This will allow Lotus to resume from URL number 6,000 and the script that crashed.