v0.7.1

Install: pip install oxihipo==0.7.1

A single-purpose release: undo 0.7.0's split-codec format-version bump,
which broke the C++ and Java implementations of those codecs. The composite fix
0.7.0 shipped is kept in full.

Fixed

• Lz4PerBank and Lz4PerColumn files written by 0.7.0 are unreadable by
  hipo-cpp and hipo-java. 0.7.0 raised the on-disk
  ext_format_version from 2 to 3 (by-bank) and 1 to 2 (by-column) when it
  appended the composite header_size table. Those version numbers turn out to
  be a cross-implementation contract: the
  hipo-cpp and
  hipo-java
feature/bybank-bycolumn-compression branches document and implement exactly
  versions 2 and 1. Measured on a JLab farm node against both:

  file	oxihipo	hipo-java	hipo-cpp
  by-bank / by-column @ 0.6.0	✅	✅	✅
  by-bank / by-column @ 0.7.0	✅	❌ failed to decode ByBank record section	❌ segfault
  by-bank / by-column @ 0.7.1	✅	✅	✅

  All three now produce byte-identical checksums on the same files, array
  (T#N) columns included.

  The bump was never necessary. The header_size table is appended after
  every other directory table, so a reader that predates it never looks that
  far — proven by patching only the version byte back on a 0.7.0 file, after
  which both other implementations read it perfectly. The library now detects
  the table by directory length instead of by the version byte, which is
  what lets the version stay fixed while the format grows.

  0.7.1 still reads the version-3/2 files 0.7.0 wrote, so nothing already
  written is lost. Rewrite them with 0.7.1 if you need to share them.

Added

• tests/composite_codecs.rs asserts the on-disk ext_format_version is 2
  (by-bank) and 1 (by-column), reading the byte back off the file. The contract
  is with other codebases, so it needed a test that fails if it drifts again.

Documentation

• The claim that the split codecs are readable only by this library was wrong
  and is corrected everywhere it appeared. The released C++ hipo4 and Java
  readers do not know wire tags 6 and 7, but the branches above do.