Call Action representations can be more helpful

[withtwoemms]

As an "Action Hero" (see #133 description for explanation)
I want the representation of a Call to also include mention of the enclosed function to be invoked
So that it's easier to understand what is happening when in a shell or logging environment

[withtwoemms]

if we have:

closure = Closure(print, 'hello!')
call = Call(closure)

then repr(call) should produce something like:

<Call(print)>