* 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)

 * minor modifs

 * the approx search now can let the PPP-tree cell to revise its distance from query - MinQueryDistanceRevisor
 * fixed a problem with precise range search on disk-oriented M-Index

 * modified query-PPP distance calculators. The main is now WSDCTight, the original one is WSDCalculator, but it was proven wrong (does not fulfill the condition that d(q,parent) >= d(q,child)
 * the "Tight" calculator uses information from an internal node about it's children

 * size of IDs (max number of objects) can be now set in the config file
 * internal cell does not store children in a Map but in an array with nulls
NOT TESTED PROPERLY YET

 * the PPPCOde navigation processors now do not use the SortedCollection at all but they use the std java.util PriorityQUeue and SynchronizedQUeue
 * the orig processors renamed
 * two unncessary classes moved from messif to mindex.private

 * distributed M-Index moved to separate GIT Project
 * modifs due to devel of dm-index

    - ID-object index (to be stored on SSD) is created by two interfaces and a class (package mindex.pppdata)
    - Refinement processor created to refine the candidates within a separate thread

 * minor modifs

 * fixed a BIG BUG in "reorganizeOverfilledBucket" that caused loss of data in case of no sub-index defined and the lowest bucket were overfilled
 * efficiency improvements in PartiallyOrderedCollection
 * much more efficient reading of PPPCOdeObjects from byte[]
 * automatic leaf size in PPPCodeAlg is now calculated so that the resulting capacities are smaller and shrinking with level
 * added richString() in PPPCodeAlgorithm
 * many smaller improvements