[FIX] ensure only one row at a time is edited, integrate dataset index in row markup...

[FIX] ensure only one row at a time is edited, integrate dataset index in row markup to create a more solid mapping between records and table rows in ListView.List (than checking the number of ancestors, which — it turns out — is a bit brittle when adding new rows at the front of the table

bzr revid: xmo@openerp.com-20110606134336-mmk00344x7gicd0z