Bug 152828 Add the projectFolder property on module
When user doesn't set the resource folder path in designer, there should be a default working path for Birt to manage the report design and find the related resources. A new property should be added on Module: name: projectFolder type:URL This property only can be given from the open design method from session but should not be set after the module initialized. Concern about the backward compatiblity issue, a new method will be added. Open design with a config argument.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/core/Module.java
* no duplicate keys.
	 * 
	 * @return a list of user-defined message keys.
	 */
	public List getMessageKeys( )
	{
		Set keys = new LinkedHashSet( );
		String[] transKeys = translations.getResourceKeys( );
		if ( transKeys != null )
		{
			for ( int i = 0; i < transKeys.length; i++ )
				keys.add( transKeys[i] );
		}
		
		
		String baseName = getStringProperty( this, INCLUDE_RESOURCE_PROP );
		if ( baseName == null )
			return new ArrayList( keys );
		keys.addAll( BundleHelper.getHelper( this, baseName ).getMessageKeys(
				ThreadResources.getLocale( ) ) );
		return new ArrayList( keys );
	}
	/**
	 * Checks if the file with <code>fileName</code> exists. The search steps
	 * are described in {@link #findResource(String, int)}.
	 * 
	 * @param fileName
	 *            the file name to check
	 * @param fileType
	 *            the file type