Chapter07 - enhance min-heap implementation

[amirsoroush]

Hi,
I made two changes to the current implementation of min-heap:

1. In both insertion(in .arrange() method) and deletion(in .sink() method) we can stop iterating as soon as we find out that there is no need to swap the values.
2. In delete_at_location() method, we need to compare the newly inserted node with its parent. Here is an example that reveals the bug:

h = MinHeap()
for i in (1, 10, 2, 11, 12, 3, 4):
    h.insert(i)
print(h.heap)
n = h.delete_at_location(5)
print(h.heap)

After the deletion the output is [0, 1, 10, 2, 11, 4, 3] which is wrong. If we draw this min-heap we could see that index 5(which has the value of 4) is less smaller than index 2(which has the value of 10)

Thanks.