tp: add flows between binder transaction pairs

Also massively cleanup this code which was highly difficult to
understand what the flow of data was.

Change-Id: I6c13118662d2e938ff8a09f2c565a68075a55d7b
diff --git a/CHANGELOG b/CHANGELOG
index 2a1bfbd..ebad664 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -4,7 +4,8 @@
   Trace Processor:
     *
   UI:
-    *
+    * Added flow arrows between binder transaction pairs (request/reply
+      and async send/async recv).
   SDK:
     *