use unified task list

[rmobis]

A few important point to mention:

• Project now includes https://github.com/OSRS-Taskman/task-list as a submodule and uses its files as the reference for task list.
• Old pets list used to be actually 3 separate lists, one for skilling pets, one for bossing pets and one for the rest. We've moved to a single list. I had to make some changes to the Pets Task List page because of that and remove the intermediary headers there. I would like to bring this functionality back in the future by using tags on the tasks.
• I've commented out a lot of unused code. Ideally, if this really isn't used anywhere, it should be removed to avoid cluttering the codebase. If you disagree, let me know and I'll uncomment it.
• I've also identified 33 templates that are not used anywhere. I have not touched them, but I'd recommend these be deleted too.

Here's the list of unused templates:

fragments/task.html
change_password_error.html
collection_log_check_error.html
dashboard_new.html
dashboard_unofficial.html
dashboard_unofficial_new.html
email-verify.html
email_change.html
email_change_submit.html
email_verify.html
export_progress.html
export_progress_error.html
faq.html
faq_backup.html
lms_change.html
login.html
new-new-faq.html
register.html
reset_password.html
reset_request.html
revert_completed_easy.html
rules.html
single-task-list.html
task-list-pets-new.html
task-list-pets.html
task_help.html
task_list.html
test_page.html
unofficial_easy_complete.html
update_completed_easy.html
username_change.html
username_change_submit.html
welcome.html