[jdt-core-dev] Updated exportplugin.xml

[Jerome Lanneluc <jerome_lanneluc@xxxxxxxxxx>]

I just updated the exportplugin.xml to adapt to the new versioning
mechanism.
- The ant script now updates the Bundle-Version in the manifest file that
is exported.
- The default target is now "export plug-in [_3.2.0]". This creates a
org.eclipse.jdt.core_3.2.0.jar file.
- The other target "export plug-in [_3.2.0.qualifier]" creates a
org.eclipse.jdt.core_3.2.0.z20051130-1036.jar file.
   Use this target if you want to use PDE import to have the plugin as a
binary project.
- The sources are now included in the jar in the 'src' root directory. This
allows the exported plugin to be imported as a source project.

IMPORTANT: You need to start Eclipse with -clean when you patch, otherwise
the new version of the plugin might not be taken into account.