(https://github.com/ruby/irb/pull/761)
* Implement `history` command
Lists IRB input history with indices. Also aliased as `hist`.
* Add tests for `history` command
* Address feedback: `puts` with multiple arguments instead of `join`ing
* Address feedback: Handle nil from splitting an empty input string
* Refactor line truncation
* Add `-g` grep option to `history` command
* Add `history` command to README
* Remove unused `*args` parameter
* Allow spaces to be included in grep
* Allow `/` to be included in grep regex
* Handle `input` being an empty string
* Exclude "#{index}: " from matching the grep regex
* Add new line after joining
https://github.com/ruby/irb/commit/3f9eacbfa9
4ee1f0fb5d