limit line length of motion text

The motion text now only even gets to be 8 cols wide on wide screens. This helps reading and opens up some space (see #657 ).

![screen shot 2014-10-07 at 5 08 42 pm](https://cloud.githubusercontent.com/assets/1239550/4538088/c159a91e-4de9-11e4-8f28-4be891eb74ae.png)
![screen shot 2014-10-07 at 5 08 46 pm](https://cloud.githubusercontent.com/assets/1239550/4538089/c15d5a32-4de9-11e4-98c1-fef0e17fdc46.png)


Closes #630