Serialize new formatter

[schveiguy]

Use the new formatter system to do serialization

[schveiguy]

@Inkrementator wondering if you have some thoughts on this as a user with current code.

While redoing the serializer, there are some breaking changes here:

1. The toJSON method now takes a policy and a formatter instead of just a char[] delegate. I found I had to do something a bit funky for this to be usable for class hierarchies (see the JSONWriterInterface and Object).
2. The default format of the serializer was not very reasonable. Some spacing between commas and colons, but no indentation and newlines. I defaulted to zero spacing. The reason for this was twofold -- it was much easier to migrate the unittests to just remove spaces than add newlines and indentation; a common default is to use no spaces for transmission over networks.

Also value your feedback @gulugulubing!

I had some inclination to give back a delegate for some kind of scoped value writing for the virtual function setup, but after implementing it for a bit, I did not like how it worked.

Ideas on how to solve that problem welcome.

[gulugulubing]

It looks good to me. It's much more symmetric with the deserialization side (Tokenizer for input ↔ Writer for output).
And on the virtual function setup, it seems fine, because the boilerplate only needs to be written once in the base class.

One minor thing — in serialize.d around the JSONValue Bool case, it looks like there might be a double-write. I fixed here #85