npm release v1.6.4

All types are now nullable.

version 1.5.5

Added #propertyType() method to retrieve the type of a single property.
Made a less-noisy update: ignore primitive arguments, instead of throwing exceptions.
Relaxed date validation requirements, to better support the Cassandra adapter.

Release 1.5.4

Object.defineProperty() now used instead of defineG|Setter.
Behavior change: properties now store their defaults upon first access; if the property is never used, nothing will be stored.
Bugfixes.