ENH: Print wall time for cellprofiler run

Makefile

@@ -11,6 +11,7 @@ CELLPROFILER := cellprofiler
 PARALLEL := parallel --eta
 PYTHON := python
 RSCRIPT := Rscript
+TIME := command time --format "Completed in wall clock time [H:M:S]: %E"
 
 # Make rule sources and targets
 SOURCES_img_raw := data/April_14_2016.tar.xz
@@ -92,7 +93,7 @@ $(TARGETS_img_zproj) : $(SOURCES_img_zproj)
 .PHONY : cellprofiler
 cellprofiler : $(TARGETS_cellprofiler) ## Collect statistics about all images.
 $(call singleton,$(TARGETS_cellprofiler)) : $(SOURCES_cellprofiler_headless)
-	$(PARALLEL) :::: $<
+	$(TIME) $(PARALLEL) :::: $<
 
 $(TARGETS_cellprofiler_commands) : $(SOURCES_cellprofiler_commands)
 	$(CELLPROFILER) $(CELLPROFILER_OPTS_HEADLESS) --get-batch-commands=$< | sed 's#^CellProfiler#$(CELLPROFILER)#' | sort -nk 8 > $@