Drop util assembly

The util assembly was originally intended to be portable between different runners, providing some useful functions. In practice, this has not worked out. Based on my work on the GUI, I've concluded that it's best if e each runner, including third-party runners, provide its own code and only use the bare-bones interface that is provided by the engine.

All of the classes and methods from nunit.util are now part of the nunit-console assembly, whose namespaces have been restructured to keep things neat.

In addition, this pull request does a few other things... TestEventHandler and ColorConsole were dependent on ConsoleOptions, in each case for a single setting. They now simply take that setting.

The copy of the framework lib used by nunit-console for its own tests has been updated. It would be better if we could figure out some other way to keep this up to date, without putting the binary into the repository.