TTMSFNCGanttProject is the non-visual data container that holds a Gantt
project's tasks, task dependencies, work-time calendar (working days, working
hours, holidays), and task states. It performs the scheduling math that turns
planned dates and durations into calculated start/end times, and one project
instance can drive several TTMSFNCGanttChart controls at once, keeping every
chart in sync from a single data source.