Make header compatible with C++ (from https://github.com/o11c/libtermkey/commit/ddd7b0c5aa10bb62dc2f7673414e9a00f11ff447) [thanks o11c]
Try tinfo before ncursesw (partially from https://github.com/o11c/libtermkey/commit/c2dd8f247a2ef9bce5ce26bfb289369643f58e09) [thanks o11c]
Unit tests should use .code.codepoint/.sym instead of not .code.number when appropriate
Be a little more lenient in locale env.var. testing for UTF-8ness