Explicit chunking on all interaction simulate models

Adds the option of explicit chunking to all interaction simulate models that were not already hooked-up. These include destination choice, location choice, and scheduling.

Also implemented a feature where the explicit_chunk setting can be less than 1. If less than one, it specifies the fraction. So explicit_chunk: 0.1 would mean that there would be 10 chunks. If greater than 1, explicit_chunk remains the total number of rows in the chooser table.