Don't round coordinates on lines, rectangles, and points in smooth mode

I was experimented with drawing dashed lines on KA using processing, but they looked wobbly.  The cause of this wobbliness is that processing rounds the coordinates before drawing.  Here's some screenshots:

Before:
![screen shot 2014-10-13 at 11 10 45 pm](https://cloud.githubusercontent.com/assets/1044413/4688318/81abbf5c-5670-11e4-87d4-be816c1f01af.png)

After:
![screen shot 2014-10-14 at 9 21 12 pm](https://cloud.githubusercontent.com/assets/1044413/4688319/87a09b94-5670-11e4-9512-bf441990b7e1.png)

This pull request enables the behaviour in the second screenshot only after users call ```smooth()```.  Since this command isn't advertised it should affect very few users.

The reason why I want to draw nice look dashed lines is because I'd like to draw some nice 3D line art diagrams like this:
![screen shot 2014-10-17 at 8 49 36 pm](https://cloud.githubusercontent.com/assets/1044413/4688340/7a8d7c14-5671-11e4-844f-00c401bc50a8.png)

It would be nice if processing-js exposed a way to use the canvas' ```setLineDash``` command... maybe as a live-editor extension.  Thoughts?