summarize trip purpose by tour mode

[bricegnichols]

Trip mode choice ASCs are defined based on trip purpose and tour mode. In the trip mode choice summary sheet we need

1. chart of trip mode share based on primary tour mode
2. chart of trip mode share based on primary tour mode and/or purpose (if its too complex to do both in a single chart just make it by tour purpose and we can make a best guess of the combinations of charts 1 and 2.)

Here's an example of how the coefficients are specified by purpose for walk trips on SOV tours:
https://github.com/psrc/soundcast/blob/asim_develop/inputs/model/activitysim/configs/trip_mode_choice_coefficients.csv#L341-L350

And again for walk trips on HOV2 tours:
https://github.com/psrc/soundcast/blob/asim_develop/inputs/model/activitysim/configs/trip_mode_choice_coefficients.csv#L364-L373