- adds man page to `EXTRA_DIST`
- `configure` checks for `a2x` only if the man page does not exist (poor
mans way of checking if we build from git or release tarball)
- fixes#50
- `__APPLE__` vs `__OS2__` - does this actually work? Would some please test on apple and give feedback?
- pthread via `AX_PTHREAD`
- version via `PACKAGE_VERSION` in `config.h`
- large file support via `AC_SYS_LARGEFILE`