Engine: rename a few constants, add javadoc
Engine: remove unused method for batch preallocation
Engine: enforce NPE if serializer is null
DBException: add first stub
Serializer: nosize serializers are not trusted
Fun.Pair: small fixes
SerializerPojo: add todo
Serializer: disable null handling on STRING and LONG
Engine: add unit tests for Engine null / delete / prealloc handling
StoreDirect: pass tests for handling null/prealloc/del values
StoreWal: pass most tests for handling null/prealloc/del values
StoreWal: pass all tests for handling null/prealloc/del values
Store: code reduction
Queues: remove locks, Node.EMPTY and use preallocation