Simulated time for unit test

This change needs some modification in EpoxyDuino that are not yet accepted.

tests/Makefile

@@ -1,6 +1,8 @@
+SUB=
+
 tests:
 	set -e; \
-	for i in *-tests/Makefile; do \
+	for i in ${SUB}*-tests/Makefile; do \
 		echo '==== Making:' $$(dirname $$i); \
 		$(MAKE) -C $$(dirname $$i) -j; \
 	done
@@ -15,14 +17,14 @@ runtests: debugtest
 	$(MAKE) clean
 	$(MAKE) tests
 	set -e; \
-	for i in *-tests/Makefile; do \
+	for i in ${SUB}*-tests/Makefile; do \
 		echo '==== Running:' $$(dirname $$i); \
 		$$(dirname $$i)/$$(dirname $$i).out; \
 	done
 
 clean:
 	set -e; \
-	for i in *-tests/Makefile; do \
+	for i in ${SUB}*-tests/Makefile; do \
 		echo '==== Cleaning:' $$(dirname $$i); \
 		$(MAKE) -C $$(dirname $$i) clean; \
 	done