0.5.0:
  document "trim" modifier
  add xo_emit_field functions
  Add xo_set_file{,_h} functions
  Fix LIBXO_* variables; add -L and -I as needed
  add --disable-silent-rules and an explicit make; s/PACKAGE-NAME/PACKAGE_NAME/; add /download/ to 'url'
  fix silliness where xo_flush_h emitted closing tag (html); make the caller (xo_message) do it
  flush after transitions; fix flush call in xo_do_emit
  mkdir the version-specific packaging dir
  use "XO_" instead of LIBXO_

0.6.0:
  Add --with-retain-size to set the size (in bits) of the retain hash buckets
  Add The Argument Modifier ({a:})
  Add retain and no-retain to --libxo
  autoconf: Add test for monitor.h
  Document quote heuristic
  go deep with nroff backslashes
  Use "ULL" for 32 bit check
  add xo_retain_clear and xo_retain_clear_all
  docs: combine two 'handles' section; move command line argument section
  handle GETTEXT when msgfmt isn't where it's supposed to be (FreeBSD)
  make 'retain' a flag (XOEF_RETAIN) instead of a role; it's simpler, and doesn't feel as tacky. "{R:}" was painful to document, which means it's painful to use.
  new xo_emit_f functions
  nuke some unused UNUSEDs
  test code: path must be static
  update test cases

0.6.1:
  fix version number (missed a commit during new-release)