Consider using infinite parking for some proposals

The Broadmoor access proposal winds up with this overall trip time distribution:

There's a ton of noise from drivers -- some short trips get pretty long, and some long trips get pretty short. Much (but not all) of this is due to parking. Because it's so scarce, some drivers spend lots of time looking for parking, until it dominates their trip time.

If we use `--infinite_parking` both for the baseline results and the edits, the results look more understandable:
There are still some driving trips that're dramatically affected:
But way less. I'll also dive into some of those to see why.

Parking scarcity and the tradeoffs of using street space for it are critical features of A/B Street, but they also require good data about the number of offstreet spots available per building and a good estimate on the total number of cars that need to park somewhere. We're making totally blind guesses about the first. The second is mostly a function of Soundcast, but since we don't distinguish car drivers and passengers, we might be trying to cram too many cars in. Any ideas for better off-street capacity estimates for Seattle specifically or in general?

And should we disable parking simulation for the purposes of the article? My experience in the area covered by the Arboretum map is that street parking is not hard to find, so it's pretty strange if our results are really sensitive to it.