moving all answers to a different package; changing hierarchy of operations and answers; answer 'ProcessObjectsAnswer' now contains 'skipped_objects' field with reasons to skip the objects

bucket dispatcher moved from VoronoiTreeIndex to MIndex; renamed mindex.algorithms.* to mindex.algorithm.*

 * added a method to calculate object count according to allObjects iterations on leaf nodes

 * version 2.8.6 - requires MESSIF version 2.1.9

    - and thus the settings parameter "ppcalculator.threads" is supported no more
 * other minor modifications in the PPP-Tree (necessary for PPP-COdes)

 * many things modified :-)

 * added the concept of duplicate DC filter that is usable especially in the memory version of multi-overlay M-Index
    - there is some commented code to be removed later

 * fixed returning of supproted operations

 * parallel & sequential MIndexInitalizer merged into a single class
These two modifications caused changes in most of the files 

 * javadoc modifications

 * fixed a bug in MultiBucket split in MIndexLeafCell (caused when the index is built by massive multi-threading)
 * updates in M-Index property generation

 * added "getParamComment" to the Parameter
 * getDynamicKey method created in MetricIndex

 * commiting last version compatible with the PPP-Code indexes built for the PPP-Code indexes (Fall 2013); the VoronoiLeaf nodes use "int objectCount" which is WRONG for M-Index multi-buckets (because of parallel processing of inserts and thread synchronization)
 * next version of M-Index should use "AtomicInteger objectCount" (it is commented out in this version)

   1) in case of multi-buckets, multi-threads, split could have been initiated on a node already split by a different thread
   2) objectCount was transient int, but should have been AtomicInteger
 * fixed approx search in case of multi-bucket when all objects from the multi-bucket are processed (much more objects were accessed than specified by the approx configuration)