subtree-merge commit 8efe1a65 of git@github.com:mirabilos/tex-unicodedomino

(unicodedomino.sty version 1.0; the only difference to 1.1, which is
only one commit further, is that 1.1 also works on Debian jessie but
for that to work includes material from LaTeX base as convenience
copy, which we don’t need at Teckids and thus/also don’t want)