New DErivBase version 1.4 (re-opened)

- the old DerivBase resource loader (version 1.3) is renamed to DerivBasePairs
- the new DerivBase resource is loaded with the new DerivBase class
- updated the descriptions of the resource's new format: for a pair of lemmas it contains rule paths instead of pairs with scores; confidence scores are computed from the paths' length
- note: before there were two different resource files, one with scores and one without, now there is only one resource file and the user has to decide whether to use the scores or not
- included the new DErivBase artifact into core/pom.xml