Replace old jrobin with rrd4j 3.5 (ticket #2684)

2019-02-10
From https://github.com/rrd4j/rrd4j/releases
Copyright (c) 2001-2005 Sasa Markovic and Ciaran Treanor.
Copyright (c) 2011 The OpenNMS Group, Inc.
Copyright 2011 The RRD4J Authors.
Apache 2.0 and LGPLv2.1

Unmodified as a base for future merges, except for omitted
files listed below.
This rev will not work; font patch to follow in next revision.

Following directories and files omitted:
converter/
core/RrdBerkeleyDbBackendFactory.java
core/RrdBerkeleyDbBackend.java
core/RrdMongoDBBackendFactory.java
core/RrdMongoDBBackend.java
demo/
graph/RrdGraphDefTemplate.java
inspector/
eu/bengreen/data/utility/