Log Message:
devel/ruby-redmine42: add package version 4.2.1

Note: ruby-redmine42 supports not only ruby26 but also ruby27.

Redmine is a flexible project management web application using the
Ruby on Rails framework, it is cross-platform and cross-database.

Redmine 4.2 introduces these new features in these categories:

Authentication / User accounts
* two-factor authentication.
* email domains restriction for user accounts.

Notifications
* Notify users about high issues (only).

Issues
* Bulk addition of related issues.
* Query links for subtasks on issue page.

Watchers
* Groups can be added as watchers for issues.
* Forum threads can now be watched.
* Watchers that are not going to receive a notification because they watch a
  non visible object (for ex: issue) are now marked in the UI as invalid.

Text formatting
* New toolbar button to insert a table.
* Wiki table column sorting.
* Languages in Highlighted code button in toolbar are now customizable by
  each user.

Keyboard shortcuts

* Switch between Edit/Preview tabs using Command/Ctrl + Shift + P.
* Bold, italic and underline text using Command/Ctrl + b, Command/Ctrl + i
  and Command/Ctrl + u.
* Submit a form using Ctrl+Enter / Command+Return.

Activity improvements
* UI options to filter activities by date or by user.
* Slight design improvements.

Another nice features
* Download all attachments at once.
* Auto complete wiki page links.
* Auto-select fields mapping in Importing.
* Fields with validation errors are now highlighted.