Support UDTs in mapper.
Throw meaningful error when trying to use a closed Cluster (JAVA-335 #send-to-testing).
Merge pull request #182 from olim7t/java335

JAVA-335: throw meaningful error when trying to use a closed Cluster.
Fix imports and trailing spaces.
Move DataType.of back to mapping module.
Move Reflection utilities back to mapping module.
Rename @UserDefinedType to @UDT.
Use @Field instead of @Column for UDTs.
Rename NestedMapper to UDTMapper and expose in public API.
Change test to cover case-sensitive field names in UDTs.
Retrieve UDTDefinition from metadata instead of building it from mapped fields.
Revert methods which had been made public.
Support enums as accessor method params.
Fix imports and trailing spaces.
Remove nested naming and DT.serialize/deserialize methods
Take protocolVersion into account everywhere
Fix passing protocolVersion to the mapper
Minor fixes, and use ? markers instead of argX in accessors
More push of protocolVersion
Fix jenkins build 117 with additional check