When clicking on multi-line segment, show info for all lines

[chosak]

A user clicking on an area where lines coincide should then see info for all of the lines that share that segment.

Even if lines are visually moved side by side, there may be 1 click handler or they may be too close togheter to effectively target (especially on touch screens), so we should not assume the user can click on an individual line in this scenario.

[chosak]

The described behavior actually works properly - if there are multiple lines that share a segment, clicking on that segment will bring up information about all of the lines. So closing this issue.

A separate but related problem is that lines that often share "the same" route, ie buses that travel down the same segment of road, are often drawn with slightly differing paths. This is because the GTFS datasets that describe their shapes might be slightly different - this is true even between different routes in the same dataset. In this case, it would be better if these lines were merged together into one. Opening new issue #62 for this.