Christian Plesner Hansen

This fixes https://github.com/spray/spray-json/issues/340 and also changes `ListBuffer` to `Map.newBuilder` since that seems like the more obvious way to build a `Map`.

Generated jsonFormatN has unexpectedly large sizeHint

1

The code generated for this line, https://github.com/spray/spray-json/blob/d0008f56bc07f7b5cd446b83184949155d40a7ff/src/main/boilerplate/spray/json/ProductFormatsInstances.scala.template#L31 is expanded to this for instance for `jsonFormat21`: ```scala def write(p: T) = { val fields = new collection.mutable.ListBuffer[(String, JsValue)] fields.sizeHint(20 * 21)...

## Changes Includes are currently handled incorrectly. Whether they occur first or last in the file they are given precedence, as if they occurred last. So if you do ```hocon...

## Changes Includes are currently handled incorrectly. Whether they occur first or last in the file they are given precedence, as if they occurred last. So if you do ```hocon...