Allow Non-tranportation uses to Share lane space

[danielBingham]

Is your feature request related to a problem? Please describe.
Right now, all features of the street are assumed to need their own dedicated lanes. However, for the non-transportation uses which don't need to allow for continuous flow of people, this isn't necessary. Street trees, street lights, transit shelters, transit waiting areas, and even parking call all share a lane by alternating uses. You can have a 12 foot lane that has a single transit shelter, multiple street trees, multiple street lights, and a disability parking space or two all fit on a single block. Right now, the only way to represent this in Street Mix would be to either do multiple slices of the block, or to compress lanes down below their realistic size so that all the intended uses fit into the same lane space (which looks pretty ugly).

This is mostly an issue with parking and transit stops.

Describe the solution you'd like
It'd be nice if there was a way to show multiple uses overlapping in the same lane, with out needing to do slices of the block. In the case of street trees, lamps, transit waiting areas, and transit shelters, you could allow them to overlap, allowing the user to choose which ones they want in the foreground and which in the back.

Another approach might be to select multiple lanes and then have a button to "combine" them into a single lane, again select which are in the foreground and which are in the back. This would center each of the uses graphics on the combined lane and take the combined lane's space as the space requirement.

Describe alternatives you've considered
Another approach might be to combine Trees, lamps, transit stops, etc into a single use for "alternating features" or something like that, allowing you to select which ones you'd like to be alternating.

Additional context