Move more generic allocation methods to the MappingEncoding

...s/af3/exploration/alg/dse/backend/opt4j/encoding/.ratings

...ation/alg/dse/backend/opt4j/encoding/MappingEncoding.java

.../alg/dse/backend/opt4j/encoding/partitionmapping/.ratings

...j/encoding/partitionmapping/PartitionMappingEncoding.java

...ation/alg/dse/backend/opt4j/encoding/taskmapping/.ratings

...ckend/opt4j/encoding/taskmapping/TaskMappingEncoding.java

...e/backend/opt4j/operator/mutate/partitionmapping/.ratings

...tor/mutate/partitionmapping/MutatePartitionDecrement.java

...tor/mutate/partitionmapping/MutatePartitionIncrement.java

...fortiss/af3/exploration/alg/dse/sysmodel/mapping/.ratings

...xploration/alg/dse/sysmodel/mapping/IMappingEncoding.java