Add a better legend

[dellisd]

Currently there is no real legend to indicate what the different lines and types of lines are showing. A small widget should be added to explain what everything visible on the map is supposed to represent.

[Zarphos]

Would it be possible to add a checkbox to the collapsible items in the legend? For example, a 'show all' checkbox for VIA rail, rather than having to enable each route individually.