h3. 1.1.5 / 2012-05-30

* Allow negative years and year range from -1048576 to 1048576 (20 bits).
* Implemented negative year with signing mask. 
* Year is no longer mandatory
* Created more specific error classes
* Implemented readonly attribute Date#bits to allow public access to the bit store for comparison in <=>.
* Moved bits.rb back into date.rb


h3. 1.1.4 / 2012-05-29

* Changed error messages for month and day to 0 - 12 and 0 - 31 respectively (since zero values are allowed).
* Changed day validation logic to only check for the presence of month (not year and month - since a year has to be set before a month and is checked there).

h3. 1.1.3 / 2012-05-28

* Bugfix: Fixed ZERO_DAY_MASK - which contained an extra bit, and was zeroing month when a day was set.
* Check that day is set to zero if month is.
* Added padding to string format for date.

h3. 1.1.2 / 2012-05-27

* Fixed syntax error in example code from README.

h3. 1.1.1 / 2012-05-27

* Updated tests and documentation.

h3. 1.1.0 / 2012-05-27

* Implemented a 23 bit store as backing store for date,
reducing the storage requirements and increasing performance 
of date objects. 

h3. 1.0.0 / 2012-05-27

* Refactored to use array backing store for element and computed date
values for better performance.
* Implemented Comparable

h3. 0.1.0 / 2012-05-26

* Initial release: