Added method to test for Time based blind SQL injection query stacking
on the affected parameter a SLEEP() or similar DBMS specific function.
Adapted libraries, plugins and XML with the above changes.
Minor layout adjustments.
* Minor enhancement to be able to specify the number of seconds to wait between each HTTP request.
* Minor bug fix to handle session.error and session.timeout in HTTP requests.
* Updated documentation.
is an integer and for some reason the resumed value from session file is
a string or a binary file, the query is executed again and and its new
output saved to the session file
