Remove unused macros.

Found with Clang's -Wunused-macros. Note that not all warnings found
were addressed. Macros that looked like part of a set were left alone,
such as the telnet IAC and GA macros in notify.c.

git-svn-id: https://pennmush.googlecode.com/svn/trunk@1786 ba372814-4f39-11de-9ad6-1127a62b9fcd