Left leaning red black tree definitions from http://www.25thandclement.com/~william/projects/llrb.h.html
Added LLRB_PREV, LLRB_NFIND and LLRB_FOREACH*
These definitions are used in a near identical way to tree.h. Just substitute RB_ with LLRB_ for most of it. Instructions for tree.h can be found here: http://man.openbsd.org/tree