Crazy idea #1: adding support for MongoDB
A type object would be the perfect way for a MongoDB document database to store and retrieve objects.

Essentially, adding optional support for the `nimongo` library in addition to the `sqlite` and `postgres` databases.

A side effect is that the `postgres` will also start supporting:

  arrays - https://www.postgresql.org/docs/9.5/arrays.html
  composites - https://www.postgresql.org/docs/9.5/rowtypes.html

since MongoDB pretty much requires that also. I'm thinking composites would be done with references to other type objects. Such as:

``` nim
composite:
  type
    Address = object
      Street: string
      City: string
      State: string

db("petshop.db", "", "", ""):
  type       
    User = object
      age: int
      name: string
      home: Address
```

I'd be happy to write it and do a PR. But wanted to see if you were interested in it for the library.