Nikita

A bit simplified code and update to Swift 5.1

1

### Checklist - [x] I've looked at the [contribution guidelines](https://github.com/raywenderlich/swift-algorithm-club/blob/master/.github/CONTRIBUTING.md). - [x] This pull request is complete and ready for review. ### Description Fixed inconsistencies in Boyer-Moore-Horspool string search algorithm...

Issues with RetryWhen

8

Now **RetryWhen** subscribes to upstream twice. This is because the **Sink** itself subscribes to the upstream in _**.init**_. Test _**testSuccessfulRetry**_() checks the number of subscriptions, but not correctly. It should...

Continuation of [Update testSuccessfulRetry and code to make it pass. #150](https://github.com/CombineCommunity/CombineExt/pull/150) ### First commit 1. When **RetryWhen** changes upstream to **Sink**, the subscription to the previous upstream must be canceled...