title: Creating "Empty" Rows in ui-grid / ng-grid
body: <p>Is there a way to conditionally add "empty" rows to a ui-grid model? The requirements for my project stipulate that we display items by date (very easy), but also display empty rows for days that don't have items on them so that users can see those gaps at a glance (much more difficult).</p>
  
  <p>Somewhat in line with what was being asked <a href="https://stackoverflow.com/questions/21149529/how-to-create-an-empty-group-in-ng-grid">in this question</a>, perhaps some sort of grouping by date and inserting an empty group for dates that don't have associated items could work...?</p>
  
  <p>I could create a whole new collection model that combines dates and my actual data and have the ui-grid use that, but that seems extremely inelegant, as it would likely entail a lot of manual reloading of everything when changes are made to the data. Ideally I'd like to just feed my collection of data rows to the grid, but still have it show an extra row with just the date field for dates that don't currently have items.</p>
  
  <p>I actually have this working in a setup using tables and ng-repeat now, but I'm looking to switch to ui-grid or similar to gain benefits of virtual scrolling, etc since I have a lot of editable (and hence, fully-bound) data.</p>
  
  <p>Thanks in advance...</p>