ImageMapUtilities improvement

This patch contains three files:
build.xml // the name of jcommon.jar was incorrect.
source/org/jfree/chart/imagemap/junit/ImageMapUtilitiesTests.java // a
unit test for my patch
source/org/jfree/chart/imagemap/ImageMapUtilities.java // the actual
patch.

The change removes duplicate area's from an image map.
see also:
http://www.jfree.org/phpBB2/viewtopic.php?
t=17524&highlight=imagemaputilities

You should be able to simply unzip this in the jfreechart top level cvs
directory, and then do a diff to see the changes. Do the diff with -uw so
as you do not see white space changes. (My IDE has removed trailing
whitespaces).

Please contact me if there are any improvements that should be made.

Cheers,
Nick.