Kas CPU-rendering backend

KAS CPU-rendering backend over softbuffer.

In its current state, this crate is usable with limitations:

• Only the SimpleTheme theme is currently supported
• Lines may be uglier than with kas-wgpu due to a lack of anti-aliasing and rounding
• Fonts appear slightly darker than kas-wgpu due to differences in the blending
• Performance seems mostly fine, though RGBA texture blending is a bit slow.

See also #610.

Copyright and Licence

The COPYRIGHT file includes a list of contributors who claim copyright on this project. This list may be incomplete; new contributors may optionally add themselves to this list.

The KAS library is published under the terms of the Apache License, Version 2.0. You may obtain a copy of this licence from the LICENSE file or on the following webpage: https://www.apache.org/licenses/LICENSE-2.0