implemented Time based blind SQL injection now is a single test file
within the lib/techniques/ folder.
Renamed lib/techniques/inference to lib/techniques/blind, it is more
approriate and adapted the rest of the libraries.
Updated ChangeLog file.
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.
