* Add get_sbrk_heap_region() method
* Use SIZE_BITS in Chunk.real_size()
* Add non_contiguous property to Arena class
* Improve Heap class
* More accurate arena detection
* Integrate Heap class into Chunk class
* Don't parse bins when no arena in find_fake_fast
* Add active_heap property to Arena class
* Add more functionality to heap classes
* next_chunk method for Chunk class
* prev property & __str__ method for Heap class
* heaps property for Arena class
* arenas command updated to reflect changes to Arena class
* Use deepcopy() in get_region() to avoid changing vmmap command output
* Import fiddling to deal with unrelated bug
* Attempt at integration with heap commands
With debug syms looks good, still issues to iron out with heuristics
* Remove redundant heap functions
* Remove redundant functions from tests
* Add system_mem property to Arena class
* thread_arena returns main_arena if single thread