* P6XML Parser failing on calendar type
* add work plan references a get_person which is not an attribute. modified to get_user to work
* Initial support for Primavera XER files
* IFC4D impl XER calendars exceptions and work time
* merged updats
* refactoring code for the 4D model to avoid duplicate code
* Assign process in the api module was missing an atrribute QuantityIn Process
* Merged changes from master
* refactoring
* resolved conflicts
* refactoring code for IFC4D
* refactoring code for IFC4D
* refactoring code for IFC4D
* Reverted the changes to IfcRelAssignsToProcess usecase
* Changed the class to be more discriptive from Utils to ScheduleIfcGenerator
* reverted changes to add_work_plan and Makefile
Co-authored-by: Dion Moult <dion@thinkmoult.com>