refactor-for-testability (#3)

Co-authored-by: jdl <jdl@desktop>
Co-authored-by: jdl <jdl@crumpington.com>
Reviewed-on: #3

peer/data-flow.dot

@@ -0,0 +1,14 @@
+digraph d {
+    ifReader   -> connWriter;
+    connReader -> ifWriter;
+    connReader -> connWriter;
+    connReader -> supervisor;
+    mcReader   -> supervisor;
+    supervisor -> connWriter;
+    supervisor -> mcWriter;
+    hubPoller  -> supervisor;
+
+    connWriter [shape="box"];
+    mcWriter [shape="box"];
+    ifWriter [shape="box"];
+}