Enhanced object creation, using column references

[dantownsend]

When instantiating a Table object, we do this (like in 99% of ORMs):

Band(name="Pythonistas", popularity=1000)

Some Piccolo queries allow you to pass in a dictionary mapping column references to values, instead of using kwargs. It's nice for tab completion, and also for catching errors.

Band.update({
    Band.popularity: 2000
}).run_sync()

It would be good to have this ability for instantiating objects too. Something like:

Band(_data={Band.name: "Pythonistas", Band.popularity: 2000})