Xerparser

Added

* Added `is_wbs` property to `TaskType` enum class. Checks if task is a wbs summary type.

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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.

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Changes

* The `task_percent` property of the `PROJECT` class now ignores Level of Effort activities when calculating percent complete. There were edge cases where the LOE activity had a remaining duration much greater than its original duration, which significantly reduced the calculated percent complete.

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* Bug fixes with validating data types for `TASKPRED` objects.

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* Bug fixes with validating data types for `TASK` objects.

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Added

* Added `resources` attribute containing a list of `TASKRSRC` objects to the `PROJECT` class. Previously, `TASKRSRC` objects were only accessible through a `TASK` object.

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