Prepare for initial release

[waywardmonkeys]

• Re-enable lints by fixing the issues. See lints disabled at the bottom of Cargo.toml
• Write additional documentation.
• Write some doc tests.
• Write normal tests.
• Do we want to keep Repeater here or is it too specific to Velato?
• What other things should we remove?
• Peniko will soon have brush-with-alpha, so some code here can go away.
• Is there code to migrate to Kurbo or elsewhere in here? What about SplineToPath?
• Can Velato be made to use this or are there going to be issues with anything that blocks that? (Do a branch of Velato with a git dependency on this crate.)
• Improve the README.md
• Decide on a channel in Zulip and update the README.
• Compare to Motion Canvas, manim, bevy_motiongfx or others to see if we're covering essentials at this level.
• Update Vello examples to use this.
• Clarify 2D vs 3D in types (actual 3D types can come later).
• Create an issue covering what's needed for supporting CSS animation features.
• Create an issue for tracking mint support.
• Support tweening for a broader range of types.