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_service2.sh

@@ -0,0 +1,10 @@
+./service2 context data out &
+PID_SERVICE=$!
+
+echo "Context" > context &
+
+echo "data" > data &
+
+cat out
+
+kill $PID_SERVICE