Run Tests in grouped order

[biohazard999]

Currently the tests are collected in a plain queue. That isn't optimal for several reasons:

1. It limits what strategy we use for testing on a scope level (run tests linear, in parallel, random order)
2. It's confusing for the end user by default, because with multiple nested groups we don't dive into subgroups first. For example:

Describe("Foo", () =>
{
	It("#1", () => true);

	Describe("Bar", () =>
	{
		It("#2", () => true);

		Describe("Baz", () =>
		{
			It("#3", () => true);
		});

		It("#4", () => true);
	});

	It("#5", () => true);

	Describe("Buz", () =>
	{
		It("#6", () => true);
	});

	It("#7", () => true);
});

Currently the execution order is:

☺ [00:00:00.0121]  Foo #1
☺ [00:00:00.0001]  Foo #5
☺ [00:00:00.0001]  Foo #7
☺ [00:00:00.0001]  Foo Bar #2
☺ [00:00:00.0001]  Foo Bar #4
☺ [00:00:00.0001]  Foo Buz #6
☺ [00:00:00.0001]  Foo Bar Baz #3

I'm not 100% sure, but I think the most intuitive way I can think of execution order would be in declared order:

☺ [00:00:00.0121]  Foo #1
☺ [00:00:00.0001]  Foo Bar #2
☺ [00:00:00.0001]  Foo Bar Baz #3
☺ [00:00:00.0001]  Foo Bar #4
☺ [00:00:00.0001]  Foo #5
☺ [00:00:00.0001]  Foo Buz #6
☺ [00:00:00.0001]  Foo #7

@hazard999 what's your thougths about that?

Because the nature how tests are collected I think we need to reorder them before execution.
I think this should be really easy with a OrderTestGroupMiddleware.
The difficult thing would be though, reconstructing the order only from the queue it self, cause there is no way to find out the executed order for nested groups...