v4.0.1 — config mistakes report errors, and runs start faster

Two fixes. Simulation output is unchanged at the same seed: FASTQs, truth VCF and BAM
records are byte-identical to v4.0.0 on H1N1 and E. coli.

Fixed

• A bad config is reported as an error, not a crash (#842). A missing or malformed
  setting, a missing file, an output that already exists, or an unreadable path now stops the
  run with exit status 1 and a message naming the key or file. These used to panic: exit
  status 101 and thread 'main' panicked at …, sometimes with nothing more than "Error
  generating configuration!". Examples of the new messages: reference is required and has no default, the name of an existing output with the overwrite_output: true hint, and a missing
  config file reported against the subcommand that was asked for (it used to read as a
  filter-reads error for every subcommand). A model file that cannot be opened is also an
  error naming the file (#846).
• Every run starts about 0.6 s sooner (#845, #846). The default sequencing error model is
  20.8 MB of JSON once decompressed, and it was parsed through a streaming reader that cost
  ~720 ms per run. Models are now decompressed into memory and then parsed: startup went from
  0.72 s to 0.09 s on a small reference. The saving is per run, so it matters most for short
  runs and many small jobs. Measured on Delta, single thread, 10x: E. coli 12.28 → 10.99 s,
  yeast 24.03 → 22.94 s, chr22 68.20 → 67.44 s.

Docs

• The install instructions no longer promise a Bioconda package (#849). conda install -c bioconda eidolon finds nothing: the recipe is in review at
  bioconda-recipes#67420. Use a
  release binary until it is merged.
• CITATION.cff cites both NEAT papers (#850).

Evidence

• Output identity: v4.0.0-era develop and the #846 build write byte-identical FASTQ R1/R2, VCF
  body and BAM records on H1N1 and on E. coli at 5x.
• tests/config_errors_exit_cleanly.rs requires exit 1, the reason on stderr and no
  "panicked" for each subcommand's config errors.
• New model-loading tests compare the new loader against the old streaming parse on the shipped
  default, and refuse non-gzip input, a truncated stream and a stream that fails its checksum.
  Each test was checked by mutation.

Not verified

• Subcommands outside the three config loaders were not audited case by case for user-input
  panics beyond the shared output-file creation, which is fixed.
• The Delta timings above come from one run during a possible Delta filesystem incident. Only
  chr22's replicates agree closely (1% spread); E. coli's first replicate read 15.3 s.
• The ~40 MB of fixed memory noted in #670 is unchanged and still unexplained.

---

Release record and verification: #852. Bioconda: not yet available; the recipe is in review at bioconda-recipes#67420. Use the binaries below.