Progress of Diff for Drupal 8

Hello again!

This is continuation to my previous post https://groups.drupal.org/node/423968 about Google Summer of Code project: Diff for Drupal 8.
We've done great progress on the diff module for Drupal 8. You can find the source code of the project at the following links: https://www.drupal.org/sandbox/lhangea/2269693 or https://github.com/lhangea/Diff/tree/master at master branch.
At the current moment the module is working fine. As an architectural solution for the beginning we chosed to use tagged services for allowing other modules to provide diff support for some field types. And it works fine with tagged services (at master branch) but after some great feedback from Berdir and corvus_ch (https://www.drupal.org/node/2267033) we realised that plugins are also great candidates for allowing other modules provide their own diff support per field type.
So I started working on replacing tagged services with plugins. For this I provide my own plugin type, interfaces, base class and manager and use the common pattern ConfigurablePluginInterface + PluginFormInterface. After this will be finished the user will be able to change the plugin used for every field type from the BO and also it will be very easy to provide custom diff support.
One quick note: the code for diff implementation with tagged services from the master branch might not be fully working since currently I'm working on the refactor_to_plugins branch and there are Drupal 8 changes happening everyday (https://www.drupal.org/list-changes). Currently I focus all my attention on finishing the refactor to plugins and that is the branch that is the most up to date with the changes and updated every day.
After 22 August which is the date when GSoC is over for this year I will continue to keep the code up to date with the changes in Drupal 8 and to maintain it.

Every feedback on implementation or functionality side is welcome and greatly appreciated.