Provides KDL serialization and deserialization for Facet types (wip)

Thanks to all individual sponsors:

...along with corporate sponsors:

...without whom this work could not exist.

The facet logo was drawn by Misiasart.

Licensed under either of:

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.