Minimal cleanup of the COMPATIBILITY section:
* Mention that the list is incomplete.
* Quoting quotes by doubling them is documented in the
Ossanna/Kernighan/Ritter Nroff/Troff User's Manual, Section 7.3.
* Our roff(7) manual documents handling of escape sequences;
besides, we partially support \w and \z now.
* Scaling widths are documented in roff(7) as well, and f is not \f.
* Negative arguments to .sp are handled now.
BIO_sock_init() no longer does anything, so stop calling it.
Minimal COMPATIBILITY cleanup:
* Mention that the list is incomplete.
* I implemented %C for groff -current, and it was accepted.
* Font family is \F, not \f.
* Escapes and scaling widths are documented in roff(7), not here.
* Quoting quotes by doubling them is now supported.