Multiway insertion algorithm (provided by the cmd-line argument --multiway...

Multiway insertion algorithm (provided by the cmd-line argument --multiway YES; or by an operation argument "multiway" (boolean))
* Use candidate objects in internal nodes in the coverage test
* Method of updating hulls after each split added -- it recomputes hulls from the scratch using all data objects rooted from the node that has been split or a child has been added into)
* Fancy print of whole tree structure added