Various functional enhancements

- HPMUtilities.FindProjects to find projects with names matching regexp
- ProductBacklogsItemInSchedule: Added Duration property
- Project: QAProjectID and BacklogProjectID now calls
ProjectOpen....Block if needed.
- Project: Clone method (to be used with a client plugin) to clone an
existing project to a new project.
- Release: ProductBacklogItemsInSchedule property added.
- ScheduleTask: Added Duration property.
- Task: Added Predecessor property.