Flask-modals

- modal backdrop problem will not occur.
- No need for an IIFE to code custom javascript.
- Python code is simplified at the expense of a few extra lines.

- Replaced parser with simple string matching
- Tested uploading of file thru a modal
- Submitter element included with form data sent to server.

- Dropped turbo.js
- Removed `beautifulsoup` dependency. Now builtin parser is used.
- Simpler and cleaner interface.
- Fixed issue regarding assets being reused in page loaded by form submit. No need of `redirect_to` and `render_template_redirect`.
- `data-turbo=false` will not be set on the body tag of every page, as turbo.js is not being used.

To be done
- Enable file upload via modal.
- Fix to send submit button value along with form data.

- Support for bootstrap 5 modals.
- Examples folder now has an app using bootstrap 5.

- Removed the `Turbo` class and converted its methods into functions.
- Updated comments in `modal.py`

- Replaced the built-in html parser with beautiful soup.
- New `response` decorator to handle calls to `render_template_modal`.
- Turbo library now always loaded.
- Links outside the modal form will not need a `data-turbo="false"` attribute now.
- Can reload the page on form submit, if needed.