Okay, so using dot for function names was probably a bad idea.

* Wouldn't work for Modules that aren't top level without making the
  module name parser greedy on finding as many dots as
  possible. (--dt-select=Foo.Bar.baz would get parsed as (TestSelector
  "Foo" (FunctionName Bar.baz))
* Probably best if the syntax is consistent for all options.

Does mean that in its current form we parse these as valid function
names --dt-select=Foo:1-bar and --dt-select=Foo:bar-1.