Issue 301

Unify the console command lines between nunit-console and nunitlite.runner.  Also, add the --testlist option to allow for a file(s) consisting of a list of tests to run.

This is currently a one-way unification to make nunit.runner the same as nunit-console (and the corresponding tests).  The changes should be able to be backed into nunit-console with no affect, but I have left that for another PR once this is merged.

Probably, the common source files should be moved into Common when that is done.
Yes, if we have to supply a valid file, TestFile is a good way to do it. Some people like Mike Feathers claim that you're not doing unit testing if you have to use a file. :-)

The object-orientation argument is a more telling one. I agree that the runner should just process the arguments it gets. OTOH, it also feels like the command-line processor should just process the command line.

@rprouse what does your object-spidy-sense tell you here?