This commit reduces the workgroup shared memory of binning to fit in
16k (by packing two u16's in a u32), and moves the config binding to
uniform, from readonly storage.
Progress toward #202
A number of things weren't being computed correctly for strokes,
including bounding boxes and also incorrectly applying y_edge logic
(which is only correct for fills).
Now that wgsl-analyzer 0.6 is released, most explicit type annotations on vec can be dropped (the exception being when it is a type conversion).
Also changes mix to select when the selector is actually boolean.
As stated by the README, the intention is for the shaders to be
provided under the terms of the Unlicense in addition to the MIT
and Apache-2.0 licenses.
While here, add a self-contained UNLICENSE file to replace the
external reference to unlicense.org.
