v0.3.4

• Add GenericVmFunction::simplify_with to simultaneously simplify a function and pick a new register count for the resulting tape
• Add bidirectional conversions between JitFunction and GenericVmFunction (exposing the inner data member)
• Add a new TileSizes(Vec<usize>) object representing tile sizes used during rendering. Unlike the previous Vec<usize>, this data type checks our tile size invariants at construction. It is used in the struct RenderConfig.
• Rethink rendering and viewport configuration:
  • Add a new RegionSize<const N: usize> type (with ImageSize and VoxelSize aliases), representing a render region. This type is responsible for the screen-to-world transform
  • Add View2 and View3 types, which stores the world-to-model transform (scaling, panning, etc)
  • Image rendering uses both RegionSize and ViewX; this means that we can now render non-square images!
  • Meshing uses just a View3, to position the model within the ±1 bounds
  • The previous fidget::shape::Bounds type is removed
  • Remove fidget::render::render2d/3d from the public API, as they're equivalent to the functions on ImageRenderConfig / VoxelRenderConfig
• Move RenderHints into fidget::render
• Remove fine-grained features from fidget crate, because we aren't actually testing the power-set of feature combinations in CI (and some were breaking!). The only remaining features are rhai, jit and eval-tests.
• Add new ShapeVars<T> type, representing a map from VarIndex -> T. This type is used for high-level rendering and meshing of Shape objects that include supplementary variables
• Add Octree::build_with_vars and Image/VoxelRenderConfig::run_with_vars functions for shapes with supplementary variables
• Change ShapeBulkEval::eval_v to take single variables (i.e. x, y, z vary but each variable has a constant value across the whole slice). Add ShapeBulkEval::eval_vs if x, y, z and variables are all changing through the slices.
• Add a new GenericVmTape<N> type, and use it for VM evaluation. Previously, the GenericVmFunction<N> type implemented both Tape and Function.
• Add vars() to Function trait, because there are cases where we want to get the variable map without building a tape (and it must always be the same).
• Fix soundness bug in Mmap (probably not user-visible)
• Add Send + Sync + Clone bounds to the trait Tape, to make them easily shared between threads. Previously, we used an Arc<Tape> to share tapes between threads, but tapes were already using an Arc<..> under the hood.
• Changed Tape::recycle from returning a Storage to returning an Option<Storage>, as tapes may now be shared between threads.
• Use Rayon for 2D and 3D rasterization
  • The threads member of VoxelRenderConfig and ImageRenderConfig is now a Option<ThreadPool>, which can be None (use a single thread), Some(ThreadPool::Global) (use the global Rayon pool), or Some(ThreadPool::Custom(..)) (use a user-provided pool)
  • This is a step towards WebAssembly multithreading, using wasm-bindgen-rayon.
  • ThreadCount is moved to fidget::mesh, because that's the only place it's now used
    • The plan is to switch to Rayon for meshing as well, eventually
• Tweak View2 and View3 APIs to make them more useful as camera types