Let file name extensions wrap to newlines when they won’t fit on one lin...

Sometimes the extensions of longer filenames will get truncated onscreen because they are not considered to be normaly word-wrappable. This screenshot demonstrates the problem:

![image](https://cloud.githubusercontent.com/assets/8218578/3842551/420de49e-1e38-11e4-90fb-86985e1e6e88.png)

These changes make the onscreen file extensions wrap to a newline when that is a suitable thing to do. The same file looks like this now:

![image](https://cloud.githubusercontent.com/assets/8218578/3842561/50ded32a-1e38-11e4-8a6f-690a71a50764.png)