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.
Now that I see it, I don't much like having the command-line processor read the file. It means we can't do isolated unit tests so easily, since we have to have an actual file we can pass to the argument.