Allow customisation of data entry categories

[jorgegil]

Since this tool is to make standard data entry, we can't have the tables editable as it can cause non-standard entries, with negative impact.

If we are to allow custom entries, this has to be catered for at the level of the customising the categories lists,. This can have an impact also on the styles.

This is a feature for later...

[jorgegil]

However, table column widths should be adjustable.