Allow for segmented parameters as proposed in #176

[JoostK]

See #176 for a detailed discussion about this feature. It allows for combining multiple route parameters into one actual input parameter, which is particularly useful when more than one parameter is required, e.g. for the new Route::bind.

[taylorotwell]

This proposal was never approved. I think it's a little too complicated honestly and not really necessary.

[JoostK]

What I'm really hoping for is a way to combine multiple parameters into one input variable, especially for the new binding feature.

This is what is allowed by this PR. However I understand that you don't want to merge it in since the syntax and clearness is not ideal. I thought of another way which is much less complicated and easier to follow:

Route::get('users/[{firstname}/{lastname}]', function($user)
{
    // $user['firstname'] and $user['lastname']
});