improve graph examples by adding logging in all examples

[jnorwood]

I noticed that graph example 3_10 has no logging. The logs are really useful for understanding and validating the relationships. Also, the ability to have delays inserted in the nodes helps validate that many orders of signal arrivals are handled properly.

In 3_10, adding relatively long delays in the source node help you understand what would be the expected graph processing if working on a live stream ... where frames arrive at a relatively long and relatively fixed interval.

I'm going to attach a fig_3_10 example with logging and delays added.

fig_3_10.zip