More intuitive UX when connecting reroutes to each other.
- Remove middle reroutes when connecting around them
- Fix earlier reroutes in chain lost when stitching
- Fix all reroutes removed when stitching in reverse
### Floating reroutes
Native reroutes can now be kept in a disconnected state.
Link chains may be kept provided they are connected to _either_ an input
or an output. By design, reroutes will be automatically removed if both
sides are disconnected.
### LinkConnector
Replaces the minimal-change effort of `connecting_links` with a more
reliable implementation.
- Subscribable, event-based API
- Uses browser-standard `e.preventDefault()` to cancel `before-*` events
- Uses standard `state` POJO - can be proxied without issue
- Structures code and separates concerns out of `LGraphCanvas`
- Link creation calls can now be made from anywhere, without the need
for a rewrite
- New canvas sub-components now live in `src/canvas/`
### Rendering
- Skips link segments by setting a `_dragging` bool flag on the LLink or
Reroute
- Moves some previously nested code to event listeners, configured in
the `LGraphCanvas` constructor
### Deprecation
`LGraphCanvas.connecting_links` is now deprecated and will later be
removed.
Until it is removed, to prevent breaking extensions it will continue to
be set and cleared by a legacy callback. The contents of this property
are ignored; code search revealed no exentsions actually modifying the
array.
- Returns object with slot, index, and pos
- Locate-by-type returns object with slot & index
- Uses standard `undefined` return for concise chaining & validation
- Free 10x perf increase over getConnectionPos (used basic random data
to test, out of curiosity)
