Textual bump and more history control

Changed

• Updated to work with Textual v0.24.0.

Added

• Added a changelog command -- loads the Frogmouth ChangeLog from the repository for viewing.
• Added the ability to delete a single item of history from the history list. (#34)
• Added the ability to clear down the whole of history. (#34)
• Added toggling the navigation sidebar between left or right dock. (#37)

Changed

• Calling any navigation pane is now a toggle operation. If it isn't visible, it's made visible; if it's visible, the navigation sidebar is closed.