Add an optional pentagon shape for block and group ports, configured via
the element-level `port-shape`, `port-kind` and `port-size` parameters.
Individual ports can override them with `shape`, `kind`, `size`,
`stroke` and `fill`. Clock ports with a pentagon shape drop the clock
triangle and default to a gray fill.
Wires attach to the outer end of the pentagon by default. With the new
`shell` parameter on `element.elmt` they attach to the inner tip
instead.
Each port is exposed as a CeTZ group with a `default` anchor plus the
cardinal sub-anchors `.east`, `.west`, `.north` and `.south` on the
pentagon's bounding box, so wires can attach to any face. For
non-pentagon ports the sub-anchors collapse to the default attach point,
and the bare `<elmt-id>-port-<port-id>` anchor resolves as before.
Add the `port-shape` and `port-shape-attach` examples and the
`gallery/test_port_shape` gallery entry.
David Stadelmann
d9abaf4a53
