Relationship max posts overflow fix

• Fixed an overflow issue with relationships, which allowed users to choose more than the maximum number of items by scrolling down
• Better Redux data handling

Fix styles for WordPress 5.3

Updates CSS to play nicely with WordPress 5.3

Better filters for PostsRelationshipControl query

See: fa94b99

• Added params to the gumponents_posts_relationship_query filter
• Added gumponents_posts_relationship_query_search_title to turn searching title on or off

GalleryControl

New GalleryControl component!

New MultiSelectControl and LinkControl

New Gumponents! 🎉

• MultiSelectControl
• LinkControl

Updated packages

• Updated Babel, Webpack and other NPM packages
• Updated coding standards

SelectImage showCaption property

• Changed the component's tag from div to figure.
• Added a new property showCaption, which optionally shows a figcaption below the image.

Better Images

More info in the image object

• The image object that is returned in SelectImage and ImageControl now store title and caption as well.

SelectImage Updates

• Added a new "Edit" modal which allows the user to edit the ALT, TITLE and CAPTION attributes of an image, just like the core/image block.
• The onChange property now also passes the full media object

Img Updates

• Also save image's TITLE attribute, if available.

New Figure component

• Added a new FIGURE component, similar to IMG
• More info here: https://github.com/junaidbhura/gumponents/wiki/Figure

Component improvements

• SelectImage now only accepts an object
• FileControl fix icon
• ImageControl allow object as value

Coding standards

• Enforce WordPress coding standards
• Added CircleCI to check
• Initialize unit tests for future
• Freeze all properties for components

FileControl

• New FileControl
• Updated ImageControl
• Refactored Redux store
• Refactored API code