- ARRAYREF/HASHREF tags
- optional string deduplication
- test and refactor regex
- test and refactor weak references
- test and refactor objects
- fast primitive array encoding
- encode string without copying
- serialized data > 2GB
- test and refactor early tracking
- don't mark as UTF-8 strings that don't contain non-ASCII characters
- check map keys are encoded/decoded correctly
- rewrite Makefile in Maven

v2:
- OBJECT_FREEZE/OBJECTV_FREEZE
