Modified realse date.
Add operation attribute to data_expr and various methods.
Refactoring RuleExpr.
Added data opration touch and changed append operation to write
operation. And added its update criteria.
Added empty rule.
Enabled rule handler to handle operation attribute of data expression
and added the concept of update order.
Fixed some bugs.
Change update criterion of touch operation.
Update examples.
Added Touch.pione and fixed bugs.
Added alias methods named "i", "f", and "str".
Add rule appliation constraints.
Added OddSelector example and modified SieveOfEratosthenes.
Update test.
Changed PIONE language to be sequence based.
Added annotations.
Improve sequence names.
Added some tests and fixed bugs.
Added prototype of annotation system.
Added sequence tests and a pione method #type.