Merge branch 'release/3.1.3'

Jenkinsfile

docs_tgrep/index.rst

oaipmh-core/pom.xml

...c/main/java/info/textgrid/middleware/DARIAHConstants.java

...main/java/info/textgrid/middleware/DublinCoreBuilder.java

.../src/main/java/info/textgrid/middleware/ErrorHandler.java

.../textgrid/middleware/IdentifierListDelivererAbstract.java

...a/info/textgrid/middleware/IdentifierListDelivererDC.java

...info/textgrid/middleware/MetadataFormatListDeliverer.java

...re/src/main/java/info/textgrid/middleware/OAIPMHImpl.java

...rc/main/java/info/textgrid/middleware/OAIPMHProducer.java

.../main/java/info/textgrid/middleware/OAIPMHUtillities.java

.../src/main/java/info/textgrid/middleware/OAI_ESClient.java

.../src/main/java/info/textgrid/middleware/OaiPmhClient.java

...main/java/info/textgrid/middleware/RecordDelivererDC.java

...n/java/info/textgrid/middleware/RecordDelivererIDIOM.java

...main/java/info/textgrid/middleware/RepIdentification.java

oaipmh-core/src/main/java/info/textgrid/middleware/Rest.java

.../src/main/java/info/textgrid/middleware/SetDeliverer.java

oaipmh-core/src/main/resources/bindings.xjb