add class for editable cell (#3761)
add class for editable cell (#3761)

* add class for editable cell

a class for editable cells allow to drive some ui features (like custom background on hover, or custom cursor). otherwise it's not always easy to know in advance which cells are editable for a given table.

* refactor allowEdit and add plain string support

* don't return from switch

* update class if cell is changed

Co-authored-by: Oli Folkerd <6011784c80910c9e8cd3ce99ca910f5d2e95a225@gmail.com>
olifolkerd/tabulator