Updated selectors and code to reflect changes on TV's website.
See also issue #116.
- Updated selectors.
- Changed how watchlists are updated. Watchlists of the same name are now removed prior to creating a new one of the same name.
- Changed how checkboxes work because of changes in DOM for the alert dialog as well for the input/properties dialog of strategies.
- Added a warning to gracefully catch setting a webhook on the alert dialog while 2fa is disabled.