Don't round when renderSmooth is true (for lines, points, and rectangles)

```renderSmooth``` is false by default so users will have to call ```smooth()``` to get the new behaviour.

before:
![screen shot 2014-10-13 at 11 10 45 pm](https://cloud.githubusercontent.com/assets/1044413/4640135/af12987e-541a-11e4-9bf6-c7635a182085.png)

after:
![screen shot 2014-10-14 at 9 21 12 pm](https://cloud.githubusercontent.com/assets/1044413/4640136/b48a5c2e-541a-11e4-9fd1-412039dbcf42.png)