Auto pattern along path for existing drawing tools

Adds a Shape drop-down to Freehand and Bezier with None, Clipboard and a few presets as options. When a path is drawn, the clipboard or preset shape is automatically applied to the path via pattern along path, allowing users to easily "draw" complex strokes and edit the skeleton. Also includes a few other proposals (bezier vs Spiro mode, access to dash and marker styles from toolbar) to show that they fit.