Role class which can be handled as a set
Consider role function for equality operator
Refactor filter functions inside Role class

There's no need for the closure in these functions.
Small reordering of methods
Merge branch 'role-set' into jokull

* role-set:
  Small reordering of methods
  Refactor filter functions inside Role class
  Consider role function for equality operator
  Role class which can be handled as a set
Fix TimeStampType convert