Module flow_age_stats and script for graphs (#231)

Introduce new module flow_age_stats with a script for graph making 
---------

Co-authored-by: Václav Bartoš <[email protected]>

Author: Michalsus

Makefile.am

@@ -8,6 +8,7 @@ biflow_aggregator \
 debug_sender \
 device_classifier \
 email_reporter \
+flow_age_stats \
 flowcounter \
 flow_meter \
 ipv6stats \

configure.ac

@@ -227,6 +227,7 @@ AC_CONFIG_FILES([Makefile
                  aggregator/Makefile
                  anonymizer/Makefile
                  backscatter/Makefile
+                 flow_age_stats/Makefile
                  biflow_aggregator/Makefile
                  bloom_history/Makefile
                  debug_sender/Makefile

flow_age_stats/Makefile.am

@@ -0,0 +1,4 @@
+bin_PROGRAMS=flow_age_stats
+flow_age_stats_SOURCES=flow_age_stats.c fields.c fields.h
+flow_age_stats_LDADD=-ltrap -lunirec
+include ../aminclude.am

flow_age_stats/README.md

@@ -0,0 +1,20 @@
+# Flow Age Stats module - README
+
+## Description
+This module is used for making statistics about the age of incoming flow data. The statistics produced are minimal, maximal and average values of the differences between the time a flow was received and its TIME_FIRST and TIME_LAST timestamps.
+
+Additionally, the module can output histograms of flow age distribution. These are written as two text files (time_first.txt, time_last.txt) that each have a table of three columns. First is the max age of the flow (the end of bin range). Second is the percentage of flows that are in that age group. Third is the flow count. By default, the bins are 0-1s, 1s-10s, 10s-20s, ... 590s-600s, >600s.
+
+## Interfaces
+- Input: One UniRec interface
+    - Template MUST contain fields TIME_FIRST and TIME_LAST
+- Output: None
+
+## Parameters
+- '-t'       If specified, the module writes a file where the tables will be outputted. (Caution - the module will overwrite files labeled time_first.txt, time_last.txt)
+
+## Graphs
+This module also comes with a script that makes use of GNUplot to make graphs from the data that is outputted into files. You can see how the graph looks like below.
+
+![ExampleGraph](example.png)
+