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.
#if PARALLEL since that's what we use to indicate if parallel execution is available at all