HISTORY:

  2.1.9:
    - added better debugging support
  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 History/Command is now valid yaml (updated samples
      to reflect this)
    - inspect for History/Command is now ruby's default 

  2.1.8:
    - greatly simplified read loop using two reader threads, one for stderr and
      one for stdout alongside a mutex to protect data.  this streamlined the code
      alot vs. the old select method including allowing removal of the linbuffer
      class.  the interface remains exactly as before however.

  2.1.7:
    - improved thread safe non-blocking read method
    - gemspec 

  2.1.6:
    - wrapped send_command in a Thread (send async) so output processing can
      commend immeadiately.  this was o.k. before, but had strange behaviour when
      using popen3 from threads.  thanks to tanaka