Rename ManifestoCanvas to MiradorCanvas

__tests__/src/lib/MiradorCanvas.test.js

src/components/CanvasLayers.js

src/components/CaptionedCanvasThumbnail.js

src/components/GalleryViewThumbnail.js

src/components/SidebarIndexList.js

src/components/SidebarIndexThumbnail.js

src/components/WindowViewer.js

src/containers/WindowSideBarButtons.js

src/lib/CanvasWorld.js

src/lib/MiradorCanvas.js

src/state/selectors/canvases.js

src/state/selectors/layers.js

src/state/selectors/manifests.js