settings keywords match when start of line

I found settings keywords not match only start line

example `Library` keyword match in Selenium2Library word.
![screen shot 2557-11-05 at 13 46 51](https://cloud.githubusercontent.com/assets/484530/4913791/845a7e9a-64b8-11e4-97ac-af31e96185c9.png)

but expect `Library` keyword to be match only start of line.
![screen shot 2557-11-05 at 13 55 10](https://cloud.githubusercontent.com/assets/484530/4913810/b84f406e-64b8-11e4-94f3-476b65957730.png)