Feature/ux fixes (#167)

* fix card toggle

* fix bug and bar marker

* reinstate timeline arrows

* adjust (hard to interpret) category y calculation

* shadows for markers as well

* return markers when there are no categories

* remove year in timeline

* make notifications optional

* WIP: render hovered counts

* show number on hover

* lint

* revert to filteredLocations

* linting

* return mapClustersToLocations

* 💄

* lint

Co-authored-by: efarooqui <efarooqui@pandora.com>

src/scss/timeline.scss

@@ -210,7 +210,6 @@ $timeline-height: 170px;
 
       .timeline-marker {
         fill: none;
-        transition: transform 0.2s ease;
       }
 
       .coevent {