resolve gather

[plastikfan]

fix the issue of gather not working because it cannot send a channel over a channel on the op. The poroblem exists because the channel is strongly typed to the item value T, meaning that only instances of T can be sent.

Of(op).SendContext(ctx, gather) // gather is the wrong type

It may be that we revert the T on Item back to interface{}, so that we can send the channel of T through the op channel (operator[T]). This would then require on both ends of the channel a type check to convert the value to the required type.

We probably need to create a new Item method: SendChContext that is specialised for sending a channel over an op channel. We probably need to combine this with a new op to compement Of, perhaps Ch (to represent a channel). If we had Ch(op), then we could still use the name SendContext, rather than SendChContext. Also, we might have to create a new member on Item, that contains the channel/op of T, that can be used by Ch. If we can find the correct solution using Ch, we can still keep Item.V as a strongly typed value.

Actually, we may be able to fix other problems by stipulating the T is not any, but 'constraints.Ordered'

[plastikfan]

this was fixed under issue #125