'RELENG_5_3_0_RELEASE'.

This commit was manufactured to restore the state of the 5.3-RELEASE image.

and close it) and "finish" (destroy the object) functions.   For backwards
compat and simplicity, have "finish" invoke "close" transparently if needed.
This allows clients to close the archive and check end-of-operation
statistics before destroying the object.

Emininated double space and hard sentence breaks.

This change also pointed out one API deficiency: the
archive_read_data_into_XXX functions were originally defined to return
the total bytes read.  This is, of course, ambiguous when dealing with
non-contiguous files.  Change it to just return a status value.

 * New read_data_block is both sparse-file aware and uses zero-copy semantics
 * Push read_data_block down into specific formats (opens door to
   various encoded entry bodies, such as zip or gtar -S)
 * Reimplement read_data, read_data_skip, read_data_into_fd in terms
   of new read_data_block.
 * Update documentation
It's unfortunate that I couldn't just call the new interface
archive_read_data, but didn't want to upset the API that much.

Correct a few other minor nits.

during lengthy extract operations.

with 'star' ACL handling, though there's still a
bit more work needed in this area.

Added 'write_open_fd' and 'read_open_fd' to simplify, e.g.,
tar's u and r modes.  Eliminated old 'write_open_file_position'
as a bad idea.  (It required closing/reopening files to
do updates, which led to unpleasant implications.)

Various other minor fixes, API tweaks, etc.