The main difference to ELinks' entity database is:
- entities not in the unicode database from 1997: Scomma, Tcomma, euro,
scomma, tcomma
- obsolete entities kept for compatibility: emdash, endash, hibar
Add header about where to get the SGML entity database from unicode.org and
summon up the locally made changes.
The root makefile is converted as well as some leaf Makefiles. This
also brings in the required infrastructure and adjusts configure.in
appropriately.
I converted only makefiles containing no configurable stuff, since
that'll require more consideration yet.