Make -v more useful. Assorted tidying
Label links to hash entries with {key...}
minor cleanup
Graphviz rankdir=LR. Less verbosity. Refactor link labels.
Add namedby_id field in lieu of reparenting
Start implementing name path for treemap UI
Simplify _get_node.
Update history for go to parent button
Remove some old fluff that's no longer relevant
Scan arena for each SV type. Much more useful.
More concrete TODOs in TODO
Incomplete name_path_html breadcrumb hack for now
Treemap placement, and node text line-height tweaks.
add PL_stashpad scan
Make sv_size onlt return true if a node was emitted. Set recurse by default.
Add a whole bunch more PL_* variables to perl_size()
Add RECURSE_INTO_ALL so perl_size() can bypass refcnt

Without this perl_size() won't see into stashes that contain items that
refer to the stash until it does the areana sweep. That works but leaves
*lots* of nodes with poor names.

This is much better from a top-level perspective. It might need refining
because now addr links will appear after the item rather than before.
Fix some (longstanding) compiler warnings.
Improve arena scan naming.
don't follow weakrefs by default in RECURSE_INTO_ALL