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.
It seems like this should be NUNITLITE because these are all features we don't support in the NUnitLite runner on any platform. For example, even if run in .NET 4.5, the runner has no abiltiy to start a process, and never will.