Bump plugin version to 5.4.0-rc.1

[noisysocks]

Changelog

Features

• Add vertical alignment support for the columns block.
• Add playsinline support for the video block.

Enhancements

• Add the Media Library button to the gallery block appender.
• Improve appearance of the block hover state on colored backgrounds.
• Move the color and font size caption styles into theme styles.
• Replace the verse block icon.
• Standardize align and className attributes for dynamic blocks.
• Remove the title from mobile inserters.
• Capitalize button labels.
• Remove menu toggling on checkbox, radio buttons clicks.
• Make the invisible image resize handlers bigger.
• Improve the alt text field description.

Bug Fixes

• Improve the format boundary styles.
• Convert void blocks properly when converting or pasting content.
• Fix the ClipboardButton component behavior in Safari.
• Fix expanding the text selection when using shift + vertical arrows.
• Fix the alignment of the third-party block settings items.
• Fix invalid HTML in some more menu items.
• Fix JavaScript error in the columns block.
• Fix radio button appearance on small screens.
• Save line breaks in the preformatted block.
• Fix edge case in the is_gutenberg_page plugin function.
• Fix toolbar position in full size aligned blocks on small screens.
• Fix double scrollbar issue in Full Screen mode.
• Fix JavaScript error when downgrading to an old Gutenberg version.
• Fix the WordPress embed block resolution.
• Fix embedding links with trailing slashes.
• Fix the preloading apiFetch middleware when initialized empty.
• Fix php notice when using widgets without description.
• Better horizontal edge detection to fix the arrow key navigation in the table block.
• Fix error in API Fetch initialization.
• Fix unwanted margin in Column block.

Documentation

• Document the block editor module.
• Add design documentation for the Panel component.
• Document webpack config extensibility.
• Clarify experimental and unstable API guidelines.
• Setup automatic API documentation for the data module.
• Improve the automatic API documentation tool.
• Enhance the components documentation:
  • FormFileUpload component.
  • MediaPlaceholder component.
  • Notice component.
  • TextControl component.
• Updates the blocks creation tutorial.
• Typos & tweaks: 1, 2, 3, 4, 5, 6, 7, 8, 9.

Various

• Implement a built-in static Gutenberg Playground.
• Override core block server-side code when using the plugin.
• Make the block editor module more reusable.
• Expose the lazy and Suspence React features in the element package.
• Avoid assuming persisted preferences state shape.
• Remove dead code from the calendar block renderer.
• Extract global CSS resets into reusable mixins.
• Replace image urls by base 64 encoded images in reusable CSS files.
• Add default empty implementation for the block types save function.
• Add a new data action to replace the inner blocks.
• Support parent data registry inheritance in the data module.
• Add extra props support for the Dashicon component.
• Add a BaseControl.VisualLabel component for purely visual labels.
• Refactor setupEditor effects to actions.
• Refactor the core/data store to be independent from the registry object.
• Remove componentWillMount usage from LatestPostEdit component.
• Add a generic e2e test for block transforms and work on its stability.
• Allow e2e test failures for php versions lower than 5.6.
• Add eslint rule to prevent incorrect truthy length property checks.
• Add eslint rule to prevent unsafe setTimeout usage in components.
• Run the local gutenberg environment in debug mode.
• Disable debug mode in local e2e tests.
• Exclude test files while rebuilding packages.
• Make E2E tests resilient against transforms added by plugins.
• Add LGPL as an OSS license.