v2.3.7
Update IdnaTest.txt from Unicode 6.3.0 to 10.0.0.
Really include standalone.sh in tarball.
Update copyright years, and enable copyright-check to notice it in the future.
tests: Add standalone.sh, fix things and use it. Seperation of IdnaTest.txt.
Export punycode APIs.
Make (some) self-tests usable standalone using system libidn2. Closes: #97.
Indent code.