v0.4.0

Splitting into multiple crates

The focus of this release is splitting fidget into a set of smaller crates, for improved compile times and modularity. This brings a clean build of fidget (time cargo build --release -pfidget) down from 60 to 45 seconds on my laptop, a significant improvement!

For the most part, this should be transparent: each smaller crate is re-exported by the fidget root crate. However, a few things got moved around to improve modularity:

• Image (bitmap and heightmap) rendering is moved from fidget::render to a separate fidget::raster module. Anything which was used by both image and mesh rendering remains in fidget::render.
• View2 and View3 have moved to fidget::gui

The helper crates can be enabled with fine-grained features on the root fidget crate, for use cases where a smaller fidget is helpful.

Other changes

• Return DoubleEndedIterator from RegTape::iter() and SsaTape::iter(), making it easier to iterate in reverse order.
• Tighter interval bounds on sin and cos (thanks @alexneufeld)