* Optimize vis_heap_chunks command
This commit optimizes the vis_heap_chunks command by:
1) precalculating bin labels instead of computing them on demand for each chunk
2) calling pwndbg.gdblib.memory.read once instead of twice in a hot loop
For `vis 2000` command ran when debugging python3 shell, the first change
cut down the execution time from almost 20s to 5s.
Another benchmark, for both 1) and 2) changes showed 19.28s->4.14s timing.
The benchmark done is included in this commit in
profiling/benchmark_vis_heap_chunks/ so that it can be reproduced e.g.
to optimize the function further or to reproduce my results.
Disconnect3d