Forcibly break cell content for columns that get too wide

This should fix #1652.

## Chrome 35.0.1916.27 beta

![screen shot 2014-04-15 at 6 22 38 pm](https://cloud.githubusercontent.com/assets/342081/2713919/42cf0816-c4ee-11e3-83bf-279ecd7e50c0.png)

## Firefox 27.0.1

![screen shot 2014-04-15 at 6 23 20 pm](https://cloud.githubusercontent.com/assets/342081/2713923/484a25fa-c4ee-11e3-963b-1b3b1c9e6062.png)

## IE9 on Win7 (via VirtualBox)

![screen shot 2014-04-15 at 6 31 23 pm](https://cloud.githubusercontent.com/assets/342081/2713928/617f40d2-c4ee-11e3-9676-754b598f2be6.png)