Added a parameter to select  where the point clouds are saved (for the p...

I just added the outputPath attribute to the ExportVtk class and the recordOnce(getParam<bool>("recordOnce", "false")) to catch it. Then if the outputPath is not empty it will prepend the file name by the corresponding path. 
Note that if the folder does not exist, it will throw an error that ask the user to make sure the folder exist.