Redistribution fixes and additions

* Made a new Hashmap to store data regarding an ongoing redistribution.
When a leaf asks for its bucket's size in order to check if any nodes need to move to or from it, any data related to the redistribution (for instance, the total number of bucket nodes in the uneven subtree, or the number of remaining buckets to be checked) is lost as soon as we exit the redistribution request function, so the need arose for a more persistent way of storing the data.
* The implementation of the redistribution is in progress (given a node, the program can tell which buckets of its subtree are either too big or too small).
* Added 3 new Message Types to prepare for extensions/contractions
* Fixed the RedistributeRequest class
* Renamed getRightRoutingTable to getRightRT to (hopefully) slightly improve readability