Change a few bits to use std::list instead of std::vector.

Change a few bits to use std::list instead of std::vector.
Vector is better than list, unless:
 - you require random access (these don't)
 - you require that the memory they are stored in are contiguous (these don't)
This will save a couple of bytes here and there perhaps (along with
much less problems with memory fragmentation and allocation).

git-svn-id: http://svn.inspircd.org/repository/trunk/inspircd@10923 e03df62e-2008-0410-955e-edbf42e46eb7