We replace all instances of `NodeIndex<usize>` in public interfaces of
`Geometry` except for `.first_rail()`, for which we make a dirty
exception.
We also improve terminology a bit:
- "joint" is renamed to "connection",
- "end" is renamed to "joint",
- "leg" is renamed to "limb".
The geometry graph is where the layout's dots, segs, and bends are
stored. The connectivity graph is where information about connected
components and relations between tem (e.g. which ones are connected with
bands) and information common to all band primitives are stored.
This removes dependency on the Slab library. We may go back to it
sometime in the future if we decide to phase out usage of Petgraph's
`StableDiGraph`.
I've temporarily removed collision/infringement detection in
`.move_dot()` because it was a lot of effort to get it right. We'll deal
with this later.
There's a panic due to mesh edges not being generated properly from
loose bends. But this commit is already very large, so I'm going to fix
this in the next one.
There's also some nomenclature changes.
`Dot` becomes `FixedDot` and `LooseDot`.
`Seg` becomes `FixedSeg`, `HalfLooseSeg`, and `FullyLooseSeg`.
`Bend` becomes `FixedBend` and `LooseBend`.
The fixed variants differ from the loose variants by being unchangeable
for the router (though probably will be pushable in some cases, but
that's for later). So typically tey're going to be the initial
conditions.
For now only the fixed variants are used even if actually loose, to
split this change into several commits.
Mikolaj Wielgus