heirloom-ng-230120

Stable release of Heirloom NG.
Differences from the last preview release:

• Notes for the library directories if linking against the GNU C library;
• Consistency within standards: the SUS rm program shouldn't have the POSIX 1003.1(2008) fix, just the main program;
• Made $(ROOT) not hardcoded --- in other words, when running make install, you can now define where you want to install without having to previously edit build/mk.config;
• Cleaned up more licence headers (if my estimations are correct, we've got rid of 3.255 lines!);
• Small update on README.md --- although it's now less readable on plain-text readers such as more(1) or pg(1), maybe a solution would be creating a plain-text version of the Markdown, like the original README.

Still to do: fix compatibility with OpenBSD greater than 5.7 (fix issue #16)