Release 0.4.0

• Add attribute references (#211)
• Fix avet upsert (#308)
• Extend benchmarks
• Add byte array support
• Add search cache
• Fix lookup search (#335)
• Fix comparators (#328)
• Add search cache (#294)
• Allow schema attribute updates (thanks to @MrEbbinghaus)
• Fix hitchhiker-tree handling (#358)
• Improve pagination performance (#294)
• Improve upsert performance
• Fix history duplicates (#363)
• Fix cardinality many duplicates (#364)
• Fix attribute translations
• Add config for index creation
• Remove uniqueness constraint for :db/txInstant
• Fix scalar binding for function output
• Fix equivalent datom input (#932)
• Fix load-entities bugs (#398, #400)
• Fix LRU cache (#404)
• Clean up code examples (#409)
• Add q as built-in (#412)
• Add meta data (#407)
• Add int? as built-in (#435)