Merge pull request #2924 from ProjectMirador/enable-wrap-add

__tests__/integration/mirador/plugins/add.html

__tests__/integration/mirador/plugins/add.test.js

__tests__/integration/mirador/plugins/priority.test.js

__tests__/src/components/WindowTopBar.test.js

__tests__/src/components/WindowTopBarPluginArea.test.js

__tests__/src/extend/withPlugins.test.js

src/components/WindowTopBar.js

src/components/WindowTopBarPluginArea.js

src/components/WindowTopBarPluginMenu.js

src/containers/WindowTopBarPluginArea.js

src/extend/withPlugins.js