Bump version to 1.4.0.

[mtias]

Changelog

• Redesigned the header area of the editor for clarity—groups content actions in the left, and post action in the right.
• Offer the ability to edit HTML on a per block basis. This change, with the above, also allows us to move the general visual/text switch to an ellipsis menu on the right.
• Initial REST API infrastructure for reusable global blocks.
• Group block settings (delete, inspector, edit HTML) on an ellipsis button.
• Added new reusable Dropdown component.
• Offer option for the button block to clear content.
• Refactor block toolbar component in preparation for some iterations (docked toolbar, for example).
• Allow partial URLs in link input.
• Avoid using state for tracking arrow key navigation in WritingFlow to prevent re-renders.
• Improve mobile header after design cleanup.
• Add focusReturn for Dropdown component.
• Updated Audio block markup to use figure element.
• Removed transition on multi-select affecting the perception of speed of the interaction.
• Show Gallery block description even if there are no images.
• Merge initialization actions into a single action.
• Fix case where the responsive treatment of the header area was hiding valuable actions.
• Fix focus styles on the inserter.
• Fix submenu visibility issue for certain users.
• Cleanup no longer used code.
• Document useOnce block API feature.

[StaggerLeee]

You are doing great job. I really like all changes and improvements.

• 3 icons are hidden (half) behind cover image.
• Please make so that HTML preview is gone when clicked outside of block. I can se already now a lot of confusion when non-coders, beginners start to delete, edit HTML tags, without knowing what they are doing. I mean not so big harm, but very confusing.