WIP: versioned queries

src/main/java/org/caosdb/server/query/Backreference.java

src/main/java/org/caosdb/server/query/Conjunction.java

src/main/java/org/caosdb/server/query/Disjunction.java

...n/java/org/caosdb/server/query/EntityFilterContainer.java

src/main/java/org/caosdb/server/query/IDFilter.java

src/main/java/org/caosdb/server/query/Negation.java

src/main/java/org/caosdb/server/query/POV.java

src/main/java/org/caosdb/server/query/Query.java

src/main/java/org/caosdb/server/query/RoleFilter.java

src/main/java/org/caosdb/server/query/SubProperty.java

src/main/java/org/caosdb/server/query/VersionFilter.java

src/test/java/org/caosdb/server/query/TestCQL.java