Fix external Nash solver in Python to use revised Game.write() interface.
Improvements to gametracer from the group at UBC.

* Add a verbose option for gambit-ipa
* Fix a bug in the gametracer implementation of ipa where division
  by zero was possible.
* Correct payoff calculations in gametracer's game representation.
Update version number and copyright date spans.
Update version number in Windows MSI build configuration.