grid api

looks like this calls for ('name', 'data'), but in the spec you say:

`Column([1, 2, 3], 'column 1')`, which is ('data', 'name')

Can we (should we) also default the column name?

`def __init__(self, data=None, name=None)`

Could it be useful to instantiate a blank column and then add to it? Should that be defaulted as well?