Use the location types and their distribution to setup the dwell times

[nunezco2]

Example:

70% homes
20% shops
10% schools

homes: 8 units
shops: 1 units
schools: 8 units

So: if no distribution is specified, we use one from a file depending on locations.

[nunezco2]

Example JSON section of the scenario file (prior to policy section):

"locations": {
    "type": "named",
    "spec": "poisson"
}

Another example, with the locations above:

"locations": {
    "type": "given",
    "spec": {
        "proportions": {
            "homes": 0.7,
            "shops": 0.2,
            "schools": 0.1
        },
        "dwell": {
            "homes": 8,
            "shops": 2,
            "schools": 4
        },
    }
},