Add G90.1 and G91.1 support to the visualizer.

For Issue #104

Parse G-Code number as a string, instead of an int. Considered using float or double, but didn't want to deal with possible x.0 strings. Using Strings in a switch statement required an update to the target platform version.

![image](https://f.cloud.github.com/assets/3976337/1809377/f480f424-6ddd-11e3-8c7e-00d69b5629ec.png)