`char` is not serializable

[ahmetsait]

iopipe.json.serialize.deserialize!char(`""`); // Error: template instance `iopipe.json.serialize.deserialize!(char, JSONTokenizer!(string, ParseConfig(false, false, false, false)))` error instantiating
iopipe.json.serialize.serialize('A'); // Error: template instance `iopipe.json.serialize.serialize!(Flag.no, BufferedInputSource!(AllocatedBuffer!(char, GCNoPointerAllocator, 32LU), immutable(NullDev), 32LU), char)` error instantiating

I don't know if this is on purpose, but allowing single character strings to be deserialized into chars would be nice regardless.

[schveiguy]

I actually would like to implement some kind of policy-based mechanism to hook serialization so you can customize however you want without having to build types. Right now, all customization is via types.

I'm not sure I love serializing a JSON string into a char, but it's not unreasonable. I'll have to think about it.

[Inkrementator]

Fwiw I work around this with fromJSON in 2 places in my code, so it would definitely be useful for me.

[schveiguy]

I think with the latest master with the new policy system, this should be doable. I'll try to make a unittest to show how it works.