init commit for BinaryHeap package

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The implementation of Heap
Fix remove and get of non-existent id
Tests for BinaryHeap
Rename heapify to downHeap to keep it consistent with upHeap

Most text-books use "heapify" but in one text-book I remember the use of
"downHeap", so I didn't make it up.
A step to MaxMinHeap
Do OOP right
Fix _upHeap and fix oop once again
Rename BinaryHeap to MaxHeap and MaxMinHeap to MinMaxHeap
A randomized test for max-heap
binary-heap: Fix rightChildIdx()
Extracted IdMap to a separate package
es3 friendly inheritance
binary-heap uses id-map
More comments on Heap implementation, linear initialization doesn't retain anything but the references to the values.
Implement heap clone with passing an array of the original's data
Fix building heap from array
Make min-max-heap's clone work in the same way it works for max-heap
Extra safety belt for binary-heap constructor
Binary-heap: refactor out the _maxIndex method