Unify "get all element lines" functions.

Merged `get_all_element_lines()` from `element-to-loose-svg.pl` into `_get_all_element_lines()` in `ComposeRunner.pm`.

*   This fixes an issue in `ComposeRunner` where previous compose items could not be referenced.
*   `element-to-loose-svg.pl` now calls the function in `ComposeRunner`.
    *   Eventually, the functionality should be worked into the `ComposeRunner` object instead.
Angle quotes.

*   Single and double angle quotes (the so-called "guillemot"—see Wikipedia for why this is a misnomer) are now defined.
*   `less` and `greater` now use full-square caps instead of half-square.