sources backup... changed:

sources backup... changed:
- added thumbnail's fastbuf to analyser iface...
  it should be better to compute the signature
  directly in gather/format/image.c instead of gatherer's
  analyser (to save one image decompression and
  hide compression errors when possible), but we still need
  analyser in the scanner
- cards contain base224-encoded signatures to save some space
- unfinished algorithm for computing and comparing signatures
- some bugfixes
- and more ... :-)