Added Makefile to build all experiments.

Makefile

+NON_DIRS=experiments/ template/
+DIRS=$(patsubst %/,%/,$(sort $(dir $(filter-out $(NON_DIRS),$(wildcard */)))))
+MAKE=make
+
+.PHONY: all clean $(DIRS) run
+
+all: $(DIRS)
+
+$(DIRS):
+	@echo Entering $@…
+	$(MAKE) -C $@
+	@echo Leaving $@
+
+clean: $(CLEAN)
+	@echo Cleaning up...
+	@for i in $(DIRS); do ($(MAKE) -C $$i/ clean); done