To-do list

Change storage to allow matrices of things to be displayed, all
using the same conventions:  main table in the middle, row and column labels to the left and top respectively, plus new matrix in 
top left --- or even larger matrices to allow labels on all sides.

Add character.only to Heading().  DONE.

Add support for nice formatting of tables of raw data. DONE

Check that arguments of Pseudo-functions using match.call. DONE

Add support for editing the labels on a table. DONE
