Since react will not render child components until the parent component
is rendered (exploratory hypotheis) We need to render the custom
component first and then access the component.  This uses a Component
function of getData().  The getData function could/should be fast
because after the render function all the data could be available via
props or state

I have not tested this with updating data from the custom component.  Or
if the custom component internally changes the data and they table needs
to resort.

This reverts commit 1fc822d.

Use the structure returned by `react.createElement` to do a render of
any child components with unrecognized types, and extract the data out
of them if they themselves return a `<Tr>`

When instantiating child components in order to render them, also pass
through the props given when creating the child component.

introduce `headerClassName` option to table, as the className to the <Thead> element is somehow ignored

This reverts commit 7a937ca.

This reverts commit 3bd8e5a.