icon with alpha and added col_description & required column's options
Added visualClear after "Add new row" button
Give focus to first column of new added row
datagridfield.js is not using jQuery: translated new focus code to pure JavaScript
fixed empty column issue when on edit
reuse plone domain for translate "required"
fixed tests
Merge pull request #7 from RedTurtle/required_column

Required column (and other features)