v0.2.5

• Faster fast levels (-5 to 2). The hash widths of the default
  parameters for inputs above 256 KiB are compiled in, which turns the hash
  shift and table mask into constants, and a candidate's validity is
  checked with a branch once the history before a block is several times
  the table's size, where that branch predicts well (the branch-free check
  stays for blocks whose table is still filling). On the first 20 MB of
  Silesia (silesia.tar, warm contexts) levels -5 to 2 compress 5-10%
  faster. Frames are unchanged.
• btlazy2 (levels 13-15) is as fast as zstd. The binary-tree walk picks
  the side to descend with a branch, as the reference does, instead of a
  branch-free select: the walk is a chain of dependent cache misses, and a
  predicted branch starts the next node's load before the comparison that
  picks it resolves. On the first 5 MB of Silesia levels 13 and 15
  compress 17% and 21% faster. Frames are unchanged.
• Sessions without a dictionary are small again. PreparedDictionary
  keeps its tables behind one Box, so it is pointer-sized and an
  EncoderSessionOwned (default D = PreparedDictionary) no longer reserves
  about 8 KiB inline for a dictionary it may not have: 40 bytes instead of
  8192 on 64-bit targets. The public API is unchanged.
• Benchmarks. Both comparison suites were rerun on this release; the
  previous run's archives were replaced.