ngircd.init: Make sure no stale PID file is left over
Update doc/Platforms.txt
doc/Platforms.txt: add Mac OS X 10.6.8
ngIRCd Release 21
NEWS/ChangeLog: Clean up version numbers and release dates
Remove wrong #ifdef in Option_String()

This fixes the following error when compiling without zlib support:

  irc.c: In function ‘Option_String’:
  irc.c:487: error: ‘options’ undeclared (first use in this function)

Reported by "der_baer" on #ngircd.