integrating changes from trunk #1770
aligning protocol buffer definitions with current trunk
merging all recent trunk changes with IIS-CDH-5.3.0 branch, bumping version to 3.1.1-CDH-5.3.0-SNAPSHOT
external references could also be inferred
added ExternalReference.query field
creating IIS-CDH-5.3.0 branch
added children entities, used by dedup
added mapping for "format" field
added authors in result message
added DataInfo to Context message
typo
merged from branch 2.0.0
introducing relMetadata field conveying information about similar relation direction
added position of citation in the bibliography of the source document