- Implement inflate algorithm in perl as a non-XS fallback.

- Implement Archive::Zip, Compress::Zlib and friends in C for performance.

- Overrides @INC to provide coexistence support for multiple
  versions of a module on the same machine.  Or use Ingy's only.pm.

- caller() from pp'ed executable should return nothing, instead
  of the current calling stacks.  Currently there's a workaround
  as PAR_CLEARSTACK in myldr/main.c, but it segfaults and hence
  is commented out by default.

- make CHECK blocks work by perl_parse the code instead of
  eval"". this should clenaly solve the above problem as well.

- POSIX.pm does not currently work with "pp -C".  Need to change
  it to either use preemptive extraction, or extract under the
  appropriate directory.

- On Cygwin, PAR_TEMP is not cleaned up even with "pp -C", because
  the cleanup time happened too late.  Need to either use spawn()
  or somehow assign win32's auto-unlink flags.

- Implement selective filtering to -F.

- Perl 5.9.2 on linux breaks PAR.

- Cygwin needs perl_5_x_y.dll to be bundled instead of libperl.dll.
  It also needs cygcrypt.dll etc, but that is another matter altogether.

- Better document all PAR_* environment variables in PAR.pm.

- Skip some binary modules (such as IO.dll) inside .par when packing standalone
  executables, if parl already contains a copy of them.
