improve redblack trees and use it to reimplement association lists and
to have better implementation of several graph algorithms.
git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@1591 b08c6af1-5177-4d33-ba66-4b1c6b8b522a
overflow handlings and garbage collection
Several ipdates to CLPBN
dif/2 could be broken in the presence of attributed variables.
git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@1474 b08c6af1-5177-4d33-ba66-4b1c6b8b522a
