Siesta currently requires you to call withParam for each individual parameter you want to add to a resource:

service.resource()
    .withParam("q": "foo")
    .withParam("page": "7")
    .withParam("order": "created_at")

This PR adds the ability to pass a dictionary of many parameters at once:

service.resource()
    .withParams([
        "q": "foo",
        "page": "7",
        "order": "created_at",
    ])

This has some arguable readability benefit, and can make it easier to build query strings whose keys vary dynamically.

It also has some performance benefit when adding many parameters, since it does not require the creation of intermediate Resource objects at each step — though the benefit is small, on the order of tens of microseconds per param.