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/JarPackageData.java
* @return a file which points to the manifest
	 */
	public IFile getManifestFile() {
		IPath path= getManifestLocation();
		if (path.isValidPath(path.toString()) && path.segmentCount() >= 2)
			return JavaPlugin.getWorkspace().getRoot().getFile(path);
		else
			return null;
	}
	
	/**
	 * Gets the manifest version.
	 * 
	 * @return a string containing the manifest version
	 */
	public String getManifestVersion() {
		if (fManifestVersion == null)
			return "1.0"; 
		return fManifestVersion;
	}
	
	/**
	 * Set the manifest version.
	 * 
	 * @param manifestVersion the string which contains the manifest version
	 */
	public void setManifestVersion(String manifestVersion) {
		fManifestVersion= manifestVersion;
	}