These tests demonstrate 3 different ways to allocate memory for the graph
viewer.

The methods:

1. global
  This method allocates a global memory pool that is used by all structs.
  It is the fastest method and should be easy to clean up. You do have to
  make sure that any pointers to the memory used by others is cleaned up.
1. malloc
  This methods does two mallocs for every iteration. It is slightly slower
  (2x as slow), but won't require as much unfragmented memory. It is harder
  to clean up this memory, as it requires an equal amount of free's.
2. array
  This method uses NSMutableArray's to store the necessary information. It is
  by far the slowest (10x slower than global) but will make use of
  Objective-C's garbage collection. This is the easiest way to go if it isn't
  too slow. Looping and creating the arrays takes about 2 seconds for 800k
  iterations. The question is if this significantly slows down the work.

Results:

   global:  0.18 seconds
  malloc:   0.39 seconds
   array:   1.90 seconds