Sonar example with callbacks.

Revision:
0:1713cdc51510
diff -r 000000000000 -r 1713cdc51510 .gitignore
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/.gitignore	Thu Sep 07 22:17:59 2017 +0000
@@ -0,0 +1,4 @@
+.build
+.mbed
+projectfiles
+*.py*