A cell when modified ( e.g. content deleted ) should have its row height
recalculated when the optimalheight attribute for that row is set.

Also tweaked the test framework to allow read/write files to be loaded, this
allows functions that modify the document content to actually work as intended

Change-Id: Ia929a194a96f5c8b870f9a49d1e27d0c34ba9c91