Upgrade to latest Marc4j library. Plus various pull-request bug fixes or enhancements:
Switch from Log4j 1.x to Reload4j.
Adjust SLF4J jars for Solr 9 compatibility.
Read properties files as UTF-8 and not ISO
Deprecate CallNumUtils.
Change SolrProxy classes to want a RecordAndDoc instead of just a SolrInputDoc.
Add better error messaging when opening/reading a property file fails.