Changes in Version 0.17
  o Fixed many bugs when the number of states were above 2.
  o Changed MLE estimation scheme
  o Function ht now output the conditional variance and not the conditional volatility
  o do.init is now FALSE by default
  o do.enhance.theta0 is now TRUE by default
Known bugs in version 0.17
  o Sometimes do.enhance.theta0 gives an error concerning uniroot
Changes in Version 0.16
  o First release