Bug 37197 Basepath for relative pathes in JAR-exporter
The basepath for the JAR-exporter is the eclipse-install-directory. I prefer it to be the root of the project (the description is saved in), so that relative pathes end inside the project. Now: <jardesc> <jar path="workspace/projectdir/jar.jar"/> Desired: <jardesc> <jar path="jar.jar"/> Reason: To make the jardesc-files portable for shared projects
org.eclipse.jdt.ui/ui/org/eclipse/jdt/ui/jarpackager/JarWriter.java
*
	 * @param resource			the file to be written
	 * @param destinationPath	the path for the file inside the archive
	 * @throws	CoreException	to signal any other unusal termination.
	 * 								This can also be used to return information
	 * 								in the status object.
	 */
	public void write(IFile resource, IPath destinationPath) throws CoreException {
		ByteArrayOutputStream output= null;
		BufferedInputStream contentStream= null;
		
		try {
			output= new ByteArrayOutputStream();
			if (!resource.isLocal(IResource.DEPTH_ZERO)) {
				String message= JarPackagerMessages.getFormattedString("JarWriter.error.fileNotAccessible", resource.getFullPath()); 
				throw JarPackagerUtil.createCoreException(message, null);
			}
			contentStream= new BufferedInputStream(resource.getContents(false));
			int chunkSize= 4096;
			byte[] readBuffer= new byte[chunkSize];
			int count;
			while ((count= contentStream.read(readBuffer, 0, chunkSize)) != -1)
				output.write(readBuffer, 0, count);
		} catch (IOException ex) {
			throw JarPackagerUtil.createCoreException(ex.getLocalizedMessage(), ex);
		} finally {
			try {
				if (output != null)
					output.close();
				if (contentStream != null)