Cleaner examples

- Use ${CXX} instead of explicit clang in the Makefile.
- More explanations.
- Use socat's fork option instead of a bash loop.
- Adds a run_* script for each example.
- Remove the useless "sleep" option in service2.

run_service1.sh

@@ -0,0 +1,11 @@
+
+./service1 data > out &
+PID_SERVICE=$!
+
+echo "Hellow World!" > data &
+
+cat out &
+
+echo "exit" > data
+
+# kill $PID_SERVICE