Handle edge case where incorrect data date is recorded in the XER file; revert to planned start date in these cases.

See change log.

Changes

• Added Node class to represent a Tree data structure - can have one parent and multiple children. ACCOUNT, ACTVCODE, PCATVAL, and PROJWBS classes now inherit from Node class.
• Updated dependency html-sanitizer to the latest version 2.2.0.
• Added is_wbs property to TaskType enum class. Checks if task is a wbs summary type.

Added

• Added wbs_root attribute to the PROJECT class. This is the root WBS node.
• Added children attribute to the PROJWBS class. Along with the wbs_root above, this forms a Tree Data Structure.
• Added children attribute to the ACCOUNT class.
• Added children attribute to the ACTVCODE class.
• Added children attribute to the PCATVAL class.

Changes

• Changed the PROJECT name from an attribute to a property. The project name is stored in the wbs_root added above.

Fixed edge case where relationship lag values were stored as empty strings rather than 0 in the xer TASKPRED table.

Fixed edge case where resource quantities were stored as empty strings rather than 0 in the xer TASK table.

Both project specific and global calendars are now included in the PROJECT calendars attribute. Covers cases where project tasks are assigned to a global calendar.

Added actual_duartion property to PROJECT class.

Some code cleanup and corrections to the python code in the README file.

• Added function file_reader which accepts a .xer file and reads it to a string object.
  • Accepts str or Path objects for files stored locally or on a server.
  • Accepts BinaryIO files from requests, Flask, FastAPI, etc...
• Added classmethods reader to the Xer class. A .xer file can be passed directly to this method, which will read and decode the file, and return a Xer object. Uses the file_reader function above.
• Changed name of function xer_to_dict to parser.