This allows to disable the 1-elem-block optimization to be able to compare the
running times with and with out it.

Queue.empty was being called with negative sizes

The same principle as when splitting blocks applies: The largest doesn't
have to be in the queue, because we already refine with respect to it
when refining the second-to-last block.

Checks if all weights are between 0 and 1.

Switches from GADT syntax to a normal ADT. This is more easily presentable in
writing as it doesn't require additional explanation and is shorter.

Although less explicit about the kind of `f`, it is more clear and easier to
replicate in publications.

This fixes up the haskell examples, so that tangling them to a file results in a
useable powerset implementation.

Creates a new module that exports commonly imported prettyprinter
modules, to cut down on the number of imports each module has to do.

These were originally separated because of some cyclic dependency that
is gone now. So in order to make the module zoo a bit more clear,
merge the two.

(With --no-sanity-checks of course)