Introduce context option

database/backends/PostgresSmartBackend.php

package-lock.json

package.json

res/css/_content.sass

res/css/login.css

res/css/login.sass

res/css/search.css

res/js/component/app.js

res/js/component/app.jsx

res/js/component/buffer.js

res/js/component/buffer.jsx

res/js/component/context.js

res/js/component/context.jsx

res/js/component/loadmore.js

res/js/component/loadmore.jsx

res/js/component/message.js

res/js/component/message.jsx

res/js/util/storage.js

templates/search.phtml