#11 simplify table cell event handling

[Rich K]

one complex thing in the current implementation is using displayObjects to generate cell html and handle events. Noting that we can grab both row and column information from the cell object itself (TD.cellIndex-1 and TD.parentNode.rowIndex, respectively), we can determine the property (and thus all the other stuff) from a generic event handler. We could then place the event handler at the table level, and have that handler dispatch the appropriate handler for the cell.