Merge branch 'bloom'

Merge branch 'bloom'

* bloom:
  bloom: avoid kernel disk flushes when we dirty a lot of pages.
  midx4: Properly decide whether to do progress in C
  midx4: Don't use Py_ssize_t, it's not in python2.4
  cmd/bloom: map only one .idx file at a time.
  bloom: Use truncate not writing zeros in create
  bloom: Don't use function pointers in tight loops
  Fix updating of bloom with additional files
  ShaBloom.init(): initialize members before the assert().
  cmd/bloom: actually, always use the same temp filename.
  cmd/bloom: use mkstemp() instead of NamedTemporaryFile().
  midx: Write midx4 in C rather than python
  midx4: midx2 with idx backreferences
  ShaBloom: Add k=4 support for large repositories
  ShaBloom prefilter to detect nonexistant objects
  mmap: Make closing source file optional