Morpho

There are several problems with the custom unit handler for an attribute. When a
custom unit is created, it does now immediately appear in the unit list for use
in other columns of a table. Appropriate 'additionalMetadata' tags are created
for the new custom unit, BUT THE UNIT IS INSERTED IN THE ATTRIBUTE WITH A
'standardUnit' TAG RATHER THAN WITH A 'customUnit' TAG.

When the custom unit is reused with another column, it is also entered with a
'standardUnit' tag, rather than 'customUnit' tag.

Also, the attribute editor window position is moved behind the datapackage
window when the custom unit dialog is brought up, putting it in the wrong window
order when the dialog is closed (This got fixed once, but is not back!)