Switched log to Scala-logging/slf4j/logback

Switched to Scala 2.11.0-RC1, simplified the factory methods for
CSPOMConstraint. Java interop moved to JCSPOM. Modified Sum due to
strange bugs in ceilDiv method. Slick is no longer supported, renamed
files using it, waiting for next version.

Support of XOR constraint via a CSPOM pattern.

Various improvements.