Merge pull request #1933 from ProjectMirador/1870-book-thumbs

__tests__/integration/mirador/thumbnail-navigation.test.js

__tests__/src/components/CanvasThumbnail.test.js

__tests__/src/components/ThumbnailNavigation.test.js

__tests__/src/components/WindowViewer.test.js

__tests__/src/lib/CanvasGroupings.test.js

src/components/CanvasThumbnail.js

src/components/ThumbnailNavigation.js

src/components/WindowSideBarCanvasPanel.js

src/components/WindowViewer.js

src/containers/ThumbnailNavigation.js

src/lib/CanvasGroupings.js