Dash-down

Added

- Add (custom) m2d CSS classes to all elements (inspired by markdown2dash)

Removed

- Removed all dependency on Python box library (dependency reduction)
- Removed references to CSS files from GITHUB

Changed

- Updated dependencies, except for `mistune` (migration to v3 postponed due to breaking API changes)

Changed

- Various version updates (now supporting up to Python 3.13), code updated accordingly
- Added option to render markdown *strings* (via the `md` argument) in additions to markdown files

Changed

- Bump `Dash` to version `>=2.5.0`, and `dash-extensions` to version `0.1.5`

Initial stable release