segogoreng

Results 2 issues of segogoreng

## Summary Continues work from #1049 by @matinFT. This PR rebases with the latest master, fixes according the [original PR's](https://github.com/stretchr/testify/pull/1049) comments by @dolmen , and also add `NotKind` to adhere...

enhancement
pkg-assert
pkg-require
enhancement: extend API

## Summary Continues work from https://github.com/stretchr/testify/pull/1723 by @FGasper . This PR rebases with the latest master. This fixes issue https://github.com/stretchr/testify/issues/1722. ## Changes Prevent stats.end() if stats.start() never ran. ## Motivation...