diff 8.x-1.0-alpha5

Diff now has a layout plugin system that allows us to ship different diff presentations.
The new default HTML Diff plugin offers rendered entity comparision with view mode selection and depends to an external PHP library. This is base on functionality previously found in HTML Diff project.
Both single and two column layouts can be switched between raw and stripped html output.
Plugins can be ordered, enabled/disabled with the first being the default selection.
The revision navigation has been separated from building the diff itself.
To reduce complexity, the diff theme selection has been dropped with a feasible default style that is more github like.

We are near Beta with only a few clean-ups left.
It's time to test, provide feedback, and help us polish the UI for a better UX.

Changes since 8.x-1.0-alpha4:

• #2798657 by yongt9412, miro_dietiker: Remove links on rendered html diff layout
• #2798663 by yongt9412, miro_dietiker: Allow select enabled view modes in rendered layout
• #2795221 by yongt9412, miro_dietiker: Use default layout plugin in diff comparison
• #2798659 by yongt9412, miro_dietiker: Merge classic and markdown plugins
• #2798663 by yongt9412: Allow select enabled view modes in rendered layout
• #2718381 by MatejZmitko, Bambell, yongt9412, nick.james, brenk28: Incorrect Breadcrumb for Markdown diff
• #2769513 by yongt9412, miro_dietiker: Offer full visual word diff
• #2790841 by yongt9412, miro_dietiker: Let the user sort layout plugins
• #2797279 by yongt9412, miro_dietiker: Check for field access when diffing
• #2796423 by yongt9412: Fix labels and padding of classic and markdown plugins
• #2795267 by yongt9412: Allow revision navigation using the same layout plugin
• #2795273 by yongt9412: Refactor module css libraries
• #2793917 by yongt9412, miro_dietiker: No duplicate lines in single col diff
• #2794329 by yongt9412: Fix schema for test view diff
• #2791943 by yongt9412, miro_dietiker: Rename Plugin/Diff to Plugin/diff/Field
• #2790837 by yongt9412, miro_dietiker: Introduce gitHub Layout plugin
• #2788153 by yongt9412, miro_dietiker: Convert default theme to a LayoutPlugin
• #2789411 by yongt9412, miro_dietiker: Remove default css to set github as default theme
• #2789437 by yongt9412, miro_dietiker: Move filter dropdown above the table
• #2788005 by yongt9412: Sort plugins based on weight
• #2788001 by yongt9412, miro_dietiker: Divide getApplicablePluginOptions
• #2766035 by yongt9412, miro_dietiker: Define default plugins
• #2784933 by yongt9412, Berdir, miro_dietiker: Use rendered field view for field builder for human display
• #2784685 by yongt9412, miro_dietiker, jonathanjfshaw: Streamline table header / row in GenericRevisionController
• #2784685 by yongt9412, jonathanjfshaw, miro_dietiker: Table keys in GenericRevisionController
• #2752725 by jonathanjfshaw, arit_nath, yongt9412: Turn EntityComparisonBase into a service