Fix regex for spaces and explain better

Closes #166, #167 
Test cases:
![screen shot 2014-04-13 at 19 53 08](https://cloud.githubusercontent.com/assets/920130/2690840/08e87b74-c367-11e3-8d88-36a29128b1da.png)
(The last number case was not addressed because I believe that it's relatively small.)

@natebrennand Can't do that /// regex literal stuff in vanilla JS!