Add y-axis labels to time period graph/ filter

[martijn-bollen]

Actual: The time period graph/ filter (bottomright pane of the 'Explore' tab) currently does not have y-ticks and y-labels.
Expected: add y-ticks and y-labels that rerender dynamically to get an idea about the number of observations of the selected species through time.
Optional: add hovering to display the number of observations for the selected species at any given date.

[Chouffe]

Thanks for reporting this issue, currently the activity is normalized (so between 0 and 1) for each species, so it makes it possible to compare two species that have very different volumes of activity (like a prey vs predator). What do you think of this?

[Chouffe]

Have a way to have a greater focus on the day and time charts only (not only as a filter).
Having some information about the timeline observations on hover (to know actual numbers).
Have a way to tweak the graphs (log scale, absolute numbers, etc).