Refactor: Use pointers to refer to elements and regulators (#84)

Previously, dyna3 used storage keys to refer to elements, necessitating passing around element containers to various functions so that they could access the relevant elements. These storage keys have been replaced with reference-counted pointers, used for tasks like these:

- Specifying the subjects of regulators.
- Collecting the regulators each element is subject to
- Handling selection.
- Creating interface components.

Also, systematizes the handling of serial numbers for entities, through a Serial trait.
And updates to rust 1.86 and institutes explicit checking of the rust version.

Co-authored-by: Aaron Fenyes <aaron.fenyes@fareycircles.ooo>
Reviewed-on: StudioInfinity/dyna3#84
Co-authored-by: Vectornaut <vectornaut@nobody@nowhere.net>
Co-committed-by: Vectornaut <vectornaut@nobody@nowhere.net>

app-proto/Cargo.lock

@@ -1,6 +1,6 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
-version = 3
+version = 4
 
 [[package]]
 name = "ahash"
@@ -89,8 +89,6 @@ dependencies = [
  "lazy_static",
  "nalgebra",
  "readonly",
- "rustc-hash",
- "slab",
  "sycamore",
  "wasm-bindgen-test",
  "web-sys",
@@ -365,12 +363,6 @@ dependencies = [
  "syn",
 ]
 
-[[package]]
-name = "rustc-hash"
-version = "2.0.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "583034fd73374156e66797ed8e5b0d5690409c9226b22d87cb7f19821c05d152"
-
 [[package]]
 name = "safe_arch"
 version = "0.7.2"
@@ -414,15 +406,6 @@ dependencies = [
  "wide",
 ]
 
-[[package]]
-name = "slab"
-version = "0.4.9"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8f92a496fb766b417c996b9c5e57daf2f7ad3b0bebe1ccfca4856390e3d3bb67"
-dependencies = [
- "autocfg",
-]
-
 [[package]]
 name = "slotmap"
 version = "1.0.7"