decompress()
  Scanner used to decompress archives (zip,rar,arj,zoo,tar,...).
  
  It is a scanner, which can decompress some of files.
  You can define your own decompressors and assing it to any extensions.
  This scanner is a filescanner only, because external decompressors
  can unpack only files. A used scanner must be also a filescanner.
  If not, use file2buffer() interscanner.
  
  Filetype is determined on file content (not on file extension).
  It can detect some exe SFX archives too.
  
  Usage: decompress(filescanner1(),[a,b,c,d]=[3,500,50MB,20MB])
  
  Where: filescanner1() is an filescanner, which can scan all files
         [a,b,c,d] is an array of 4 numbers:
           a = max number of recursions
           b = max number of decompressed files
           c = max disk usage with all of decompressed files
           d = max address space usage