Exported Config.Data & Merge()

[jswank]

Renamed Config.data to Config.Data and merge() to Merge().

I found these minor changes to be convenient wrt/ setting defaults for optional configuration directives or overriding config directives based on other input.

    defaults := map[string]interface{}{
        "foo": "on",
        "bar": 1,
        "baz": true,
    }

    config := &jconfig.Config{}
    config.Data = defaults

    config.StringMerge(`{"foo": "off"}`)

    fmt.Printf("optional config baz: %t\n", config.GetBool("baz"))