#21 Eyedrop should match window behavior

[Miguel Munoz]

The behavior of the eye-drop tool should match what it was on Windows. On windows, after using the eye-drop to pick a color, the selected tool would immediately revert back to what it was before the eye-drop was selected. This makes it more useful because, once a color is selected, we want to go back to drawing with the previously selected tool. This shouldn't be hard to do.