Visualizations for tracing

[sliminality]

Ideas from Nick:

• For a series of captured stacks: a call tree with counts (can be inverted too). For example, trace the stack whenever we call the free function, and then aggregate this into a call stack:

Total Count | Self Count | Stack Frame
------------+------------+----------------------------
        123 |          0 | do_tick
         67 |          0 | ├── physics
         67 |         67 | │   └── destroy_collision_node
         56 |          0 | └── render
         43 |         43 |     ├── finish_draw_rect
         13 |         13 |     └── finish_draw_circle

• For any scalar data, ie the arguments to and values returned from some functions, we could draw histograms. This would be neat combined with tracing the requested sizes of allocations, for example:

value  ------------- Distribution ------------- count
   16 |                                         0
   32 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@       169
   64 |@@@                                      16
  128 |@@                                       10
  256 |                                         0