Made a whole bunch of changes.

Draw and SimpleTool back to tzk.image.tool.
This is what "public" is for.
We want separate packages. It keeps things clean.
SimpleTool now has field toolButton. Will link this with de/select.
toolButton will probably end up being type JToggleButton.
A tool is selected only once instead of every time we click in the drawingArea

Updated DrawingArea so that preview should not break anymore.
In the process, I ended up losing drawingArea1 and readding it.
We may need to update the layout now.
Found that in order to add a custom class, everything must compile.
Learned much.

Tried different implementations of SimpleTool (Class vs Interface).
Reverted. Still not sure if this is the best way, but it works.
Learned much.