Factor out thumbnail galleries into a PostGallery component. This changes the html structure so that post galleries on all pages are always wrapped in a `.posts-container` class. This fixes an issue with thumbnails on the pool show page not being aligned correctly on mobile, like they are on the post index page. This also affected thumbnail galleries on other pages, like wiki pages and user profiles.
Components
Components are used to encapsulate common UI widgets used throughout the site. This includes things like comments, tag lists, post thumbnails, paginators, and other things used repeatedly throughout the site. Components encapsulate a widget's HTML, CSS, and Javascript together so that all the code for a component is in a single place.
This uses the ViewComponent library.
Components are similar in concept to React components.