Implementation of our own classes for the JTreeMap

[Fei]

I have tried to play with the JTreeMap example today, and it took me a
long time to display the date as a real date rather than miliseconds
in the tooptip. The example code is surprisingly sloppy, there are
quite a bit of unfinished code. I that why it's just an example.

I think we can and should implement our version of the following
classes to fit our needs:

- DefaultToolTip and DefaultToolTipBuilder for displaying the tool tip
- DefaultValue for handling the date type value
- ColorProvider for better color display. (red green color bar without
the negative part should be pretty good)

I also got some sloppy code working for these classes, should be good
for the demo after some quick fix. So now I want to make the sensor
data part really hook up with the application, rathar then still using
the fake data. Maybe something like a button that whenever you click
it, it collects the data and writes the file, then the application
would read the file again.

[Jianfei Liao]

Oh, and let's try to get the applet running as the webapp in tomcat, without wicket like what professor said in the other thread.