Improvements to DC map frontend.

[adunkman]

Related to #90 — this PR adds the random number specified in the issue.

I think the issue may actually be completed at this point, or maybe we can clarify what remaining work is needed.

Additionally, I did some tidying:

• Removed an unused parameter.
• Added quadrants to the street names.
• Dropped some margin to fix a layout issue.

Here’s what it looks like!