HISTORY:

  2.4.0:
    - added ability to specify stdin for Session::Bash and Session::Sh

        sh = Session::new

        sh.execute 'cat', :stdin => io
        sh.execute 'cat', :stdin => string
        sh.execute 'cat', :stdin => stringio

  2.3.0:
    - fixed warning of @debug being un-initialized

  2.2.0:
    - added a private munged version of Open3::open3.  the builtin one causes
      the child process to become a child of init, this was very inconvenient
      because it was sometimes hard to crawl proces trees - the parent was lost.
      now the seesion is a child process that has been detached using
      Process::detach.  this results in less suprising behaviour; for instance
      sending signal TERM to a process results in any sessions it had open dying
      as well.  you can use Session::use_open3=true or
      ENV['SESSION_USE_OPEN3']='1' for the old behaviour if you need it.
    - added Session::Bash::Login class.  this class opens a session which has
      all the normal settings of a bash loging shell (.bashrc is sourced).  this
      if often convenient as paths, aliases, etc. are set as normal.
    - moved the Spawn module inside the Session module.  now the Session module
      is the namespace for everything so using session pollutes namespace less.

  2.1.9:
    - fixed bug where setting track history after creation caused later failure in
      execute (@history =[] only in ctor).  thanks leon breedt
      <bitserf@gmail.com>!
    - updates to README
    - included session-x.x.x.rpa file - thanks batsman <batsman.geo@yahoo.com>
    - to_str/to_s/to_yaml for H