Add exception middleware and related files.

Create a package for taskapp views and break the views into task and textbook. Now all the view functions common to any two entities along with all tasks related views sit in task module. Even if the view is not directly related to the task entity, it sits in the task module since task is the base for every other entity in the application.

Move the configuration module to the helpers package and adjust the imports.

Create a separate package to hold all the PyTask sitewide helpers.

Add a utility script with a function to remove Textbook from current textbook chapter tasks.

Change password reset email URL to hard coded URL.

Use django-registration module url reverse methods than the django's.

Use the form helpers templatetags instead of hard coding forms.

Change form related properties.

Display list of tasks related to a Textbook and allow coordinator to create them.

Style fixes.

Allow editing of tasks even to coordinators and mentors.

A task should be able to have sub tasks. So sub tasks are linked to their parents.

Add a view, form and related URL for chapter creation under textbook.

Chapters must be created from the Task model. Textbook model don't exist anymore.