WavePacket (C++/Python) Files

Major changes for version 0.3.3:

* Added basic plotting to the Python interface
  Only simple 1D plots, but the technology is there
* reduced number of cases where you need to cast explicitly in the Python interface
* cleaned up relaxations
  Removed OdeRelax (slow, useless), added propagation to negative times to ChebychevRelax
* reorganized operator hierarchy for further manipulations
  in particular, cleanly separated real- and complex-valued operators,
  should give a minor speed gain as a side effect
* several usability improvements
  for example, you can give simply the channel number to project onto a channel