Show attributes and values for SAMPLE columns

This adds an "uber column" of INFO, SAMPLE_1, ... SAMPLE_n
with respective attibutes/values uderneath them.

fixes #67
Added a reference to the note. Hard/impossible to do good validation on this via propTypes.

In theory, it's not in the spec that they'd be in order, but in practice all objects will have insertion-ordered keys, less numeric keys (which will not occur here).