update readme
tweak
remove stale comment, Nada's quine code works great even for larger N
LOGIC-90: <=fd constraint could diverge

The `-relevant?` implementation for `<=fdc` was wrong. If we have two
singleton domains we just check that they are not <= to each
other. However we can also discard the constraint if we have
`interval-<`. Added test case.
update changes
bump version
[maven-release-plugin] prepare release core.logic-0.8.0-beta5
[maven-release-plugin] prepare for next development iteration