Adding in basic stylings for three views.
Adding a map and two markers to it for the current directions. Next steps: moving next and prev click listeners within map function scope to re-render with new directions each time
Added in code to make the map recenter to the new markers added for each leg of the journey, deleting the former markers from the map first.
Added in working conditional for 'next' button that checks against the length of the directions instructions array
Adding in map styling
Added edits to map styling, and changed the polyline color
Added in placeholder user icon