Allow retrieving compressed chunks

VDDK always decompresses the chunks it retrieves. However, some
callers may be interested in the compressed chunks, which may
be forwarded to another service involved in the backup process.

We'll add a read flag (skip_decompression). If set, the read
operation will return a "ReadResult" container, containing
a list of fragments and their compressed / decompressed lengths.

If the returned buffer size matches the AIO buffer size (which
now becomes configurable), at most one fragment will be returned.

While at it, we're adding perf tests that check various AIO buffer
sizes, cross checking against VDDK.

README.md

@@ -4,6 +4,10 @@ OpenVixDiskLib is an open-source Python replacement for VMware VDDK's
 `VixDiskLib` NBD path. It reads and writes VMDK contents over vSphere
 NFC without the proprietary VDDK SDK.
 
+AI tools (Cursor + Grok 4.6) have been heavily used to reverse engineer the
+NBD and NFC protocols, obtaining a working VDDK replacement in a few hours and
+comprehensive testing in a matter of days.
+
 The Python package is `openvixdisklib` (lowercase, following usual
 Python naming).
 
@@ -18,7 +22,7 @@ Implemented against vCenter 8 / ESXi 8. Default transport is `nbdssl`
 
 - `VixDiskLib_ConnectEx` (UID credentials)
 - `VixDiskLib_Open` (datastore path, read-only or read-write)
-- `VixDiskLib_Read`
+- `VixDiskLib_Read` (optional ``skip_decompression`` packs FastLZ extras)
 - `VixDiskLib_Write`
 
 Not implemented: compression open flags other than FastLZ, CBT /
@@ -112,7 +116,8 @@ tox -e integration -- --runslow
 
 Compare write/read throughput of OpenVixDiskLib and native VDDK
 (`64KiB`, 129-sector, and `32MiB` transfers; `nbdssl` and `nbd`;
-plain and FastLZ):
+plain, FastLZ, and OpenVixDiskLib FastLZ ``skip_decompression``;
+AIO sessions 64 KiB×1, 1 MiB×1, 2 MiB×1, and 2 MiB×4).
 
 ```bash
 tox -e perf