use fancy .In macro for includes. from Jan Klemkow. ok jmc schwarze

convert to new .Dd format;

section reorder;

- typos
- new sentence, new line
- clean up .Xrs

Trailing whitespace begone!

Add FreeBSD tags

This is OpenBSD.

sync with FreeBSD (rwlock, gc thread, man pages)
add (broken) mips md stuff
fix some const warnings
add sigaltstack() stub
another hash at getting shlib auto-init to work (mips/elf and i386/a.out)