Improve the cond func

[bep]

There are two items that I want to address:

1. Make it use the same "truth" function as if/with/not/and -- but we should think a little if this would break stuff
2. Lazily invocation of passed funcs/methods

Basically I want to be able to do something ala:

n := cond .File .File.Filename .Name

Maybe not the best example, but imagine a nilpointer scenario etc.