Use alternate syntax for includes.

Fix errors.

Make it work with Meson.

Add src to include directories.

Use Meson-friendly structure.

Some config items may refer to other config items values for
transformations.

Add tests for int config items.

Support for C++.

Specify build instructions.

Define library.

Separate types from main definition.

Use appropriate name for null transformer.

Complete all int types for configs.

Extract source files from Izanagi.