added validation/aggregating/pipeline/validations_on_sparse_datasources.odg

validation/aggregating/pipeline/aggregating_validations_pipeline.odg: made "diff tables" the same size as the other major labels

validation/aggregating/pipeline/aggregating_validations_pipeline.odg: added CSVs export arrows and import process arrows, as decided in conference call

added validation/aggregating/pipeline/aggregating_validations_pipeline.odg with .png export