* Add Greek letters and symbols:
   - Heta (`U+0370`, `U+0371`);
   - Sampi (`U+0372`, `U+0373`, `U+03E0`, `U+03E1`);
   - Greek Lower Number Sign (`U+0375`);
   - Pamphylian Digamma (`U+0376`, `U+0377`);
   - Capital Kai Symbol (`U+03CF`);
   - Qoppa (`U+03D8`, `U+03D9`, `U+03DE`, `U+03DF`);
   - Stigma (`U+03DA`, `U+03DB`);
   - San (`U+03FA`, `U+03FB`);
   - Rho with Bar Symbol (`U+03FC`).