DOC: Copyright notices.

src/main/java/caosdb/server/caching/JCSCacheHelper.java

src/main/java/caosdb/server/database/BackendTransaction.java

...a/caosdb/server/database/CacheableBackendTransaction.java

...er/database/backend/implementation/MySQL/MySQLHelper.java

...er/database/backend/transaction/RetrieveSparseEntity.java

...ver/database/backend/transaction/RetrieveVersionInfo.java

src/main/java/caosdb/server/datatype/ReferenceValue.java

src/main/java/caosdb/server/entity/DeleteEntity.java

src/main/java/caosdb/server/entity/Entity.java

src/main/java/caosdb/server/entity/RetrieveEntity.java

src/main/java/caosdb/server/entity/Version.java

...n/java/caosdb/server/entity/xml/VersionXMLSerializer.java

src/main/java/caosdb/server/jobs/Job.java

src/main/java/caosdb/server/jobs/core/CheckRefidValid.java

...urce/transaction/handlers/SimpleDeleteRequestHandler.java