Separate Essentials Plugin SDK and Dashboard

In order to be able to move Essentials plugins that pertain to a certain other BRE/Hippo CMS project into the project and lifecycle of that project, Essentials' Plugin SDK should be split off into a separate project, such that both the Essentials dashboard (web app) and the (external) plugins can depend on the plugin SDK without introducing circular dependencies.

When splitting off the plugin SDK, care should be taken to preserve the history of its sources. Here [1] is a simple article on how to go about it.

[1] https://help.github.com/articles/splitting-a-subfolder-out-into-a-new-repository/