1.x: fix: bounded replay() not requesting enough for latecommers

[akarnokd]

Fixes the bug reported in #3452.

The fix involves 3 changes:

• First, each node in the bounded buffer receives an incrementing index whenever they are created. The root node starts with 0, the first value's index will be 1 and so on.
• In the replay logic, the very first time the current node is captured, the node's index is added to the totalRequested amount of the subscriber. Since this is always one less than the max requested that far, there is no point in calling manageRequests() at this point.
• Third, the pinning of the current node has to happen before the child requests, otherwise the difference would manifest before the compensation and some elements may get missed.

In addition, there was a missing r-- in the emission loop and thus the operator could have overflown its child subscriber.

[benjchristensen]

Don't have the time to fully grok this, but the changes look okay and I trust @akarnokd on this. So 👍

[akarnokd]

Thank you @benjchristensen. Since replay() is one of the most complicated operators, I'd like @abersnaze or @stealthcode to look at it before it ends up in 1.0.15.

[stealthcode]

👍