we need to fix T1969 before opening this up, and in most cases what one wants
is really /randomwalk anyway

Closes T1888

it is the only sane way to have decent semantics in presence of edge
restrictions, without having to visit twice all successors

Closes T2077

in wait for a migration to a more propre solution, i.e.,
https://docs.python.org/3/library/importlib.html#module-importlib.resources

it is a marginal dependency of LAW, for a fringe tool that we do not use

while at it, switch string formatting to f-strings

... and it is brittle enough to make the overall doc build fail fairly
often. We will reconsider building it when we can actually shipped it (see
T1971)

fix docs.s.o build failure

This avoids that the MPH step loads the full (decompressed!) nodes file in
memory.

To achieve this, force usage of /bin/bash as shell to run the various steps.

before this change it wasn't interpolated in case java_tool_options was given
in configuration (and contained '{logback}')

- add logging for begin/end of loading steps (.mph, .order)
- add logging of local speed for pid->node, because average speed might be
  skewed by temporary sort hangs

no longer needed extra indirection