Mpxj

* Improve reliability when reading certain Phoenix files.
* Ensure multiple trailing nul characters are stripped from text when reading schedules from a Primavera database.

* Improve accuracy of identifying null tasks in certain MPP files.
* Improve accuracy of identifying valid tasks in certain MPP files.
* Ensure hierarchical outline code values are read correctly from MSPDI files.
* Improve support for files produced by recent versions of FastTrack.

* Added support for Phoenix 5 schedules.
* Improve handling of null tasks read from MPP files.

* Introduced the BaselineStrategy interface and implementing classes. (Note: this includes a breaking change if you were using the ProjectFile.setBaseline method and supplying a lambda. You will now need to implement a BaselineStrategy and set this in ProjectConfig before setting a baseline).
* Improved accuracy of baseline attributes for Primavera schedules.

* Add Sprint ID and Board Status ID attributes to task.
* Introduce the TimeUnitDefaultsContainer to allow constants for time unit conversions to be obtained from both project properties and calendars.
* Duration attributes are no longer returned as Duration instances by the ruby gem, they are now returned as floating point numbers. By default, durations are expressed in seconds. A new optional argument to MPXJ::Reader.read allows you to change the units used to express durations. (Note: this is a breaking change for users of the ruby gem)
* Update JsonWriter to use a relevant calendar when converting durations.
* Ensure default calendar is set correctly when reading XER and PMXML files, and P6 databases.
* Use default hours per day/week/month/year when reading P6 XER files or databases if these values are not present.
* Ensure that the minutes per day/week/month/year attributes are copied when a calendar is copied.
* When reading P6 schedules, roll up calendar for WBS entries when child activities all share the same calendar.
* Generate missing minutes per day/week/month/year for calendars read from P6 schedules.
* Inherit minutes per day/week/month/year from base calendars (Note: minor method signature changes on ProjectProperties and ProjectCalendar).
* Allow explicit values to be set for project minutes per week and minutes per year.
* Fall back on defaults for project minutes per day/week/month/year attributes.

* Add Planned Start and Scheduled Finish to project properties.
* Add attribute_types method to Ruby classes.
* Updated to use POI 5.0.0.
* Corrected source of Must Finish By project property when reading XER files or P6 databases.
* When reading PMXML files, ensure that the activity calendar is set before calculating slack.
* Remove unused field TaskField.PARENT_TASK.
* Ensure task Unique ID and task Parent Unique ID attributes are treated as mandatory when written to JSON.
* Fix an issue with Ruby gem where a task's parent was not being retrieved correctly in some circumstances.